I searched through various tire threads on TWW and didn't see this topic discussed yet. I wanted to get some of your opinions. I recently read somewhere that, regardless of FWD or RWD, it is preferred to keep the best tires on the rear axle of the vehicle. Reasoning being that oversteer is more difficult to control than understeer.

I ask because I am driving a car with RWD and my rear tires display much more wear than my front tires. I wanted to get a tire rotation to slightly delay purchasing a whole new set of tires. A few mechanics highly doubted and discouraged this idea. I wanted to see what some car enthusiasts think before rotating.

[Edited on May 29, 2009 at 5:56 PM. Reason : 1]

5/29/2009 5:55:53 PM

wait mechanics doubt exactly what about tire rotations?

are these the same mechanics who will sell you the new set of tires?

5/29/2009 5:59:57 PM

false. good tires (good tread depth) should be up front to handle hydroplaning. your average car at average speed won't be understeering or oversteering, but it sure will hydroplane.

Besides, there's nothing wrong with bald tires gripwise on dry pavement

5/29/2009 7:14:54 PM

^while I ignore the mechanics when they say "you should put the new tires on the back" I had an experience recently where it almost bit me in the ass.

One morning I had two new tires installed, and I had them put them on the front. It rained that morning, but stopped before I drove home. Nonetheless the troads were still damp. I like the take the tight turns where Capital turns into Dawson quickly for thrills. So as I flew through them the back of my car flew WAY THE FUCK OUT. Surprised the fuck out of me, lol. There weren't any cars around though so I caught it no problem and just kept driving. Anyway after that I'd push the car in turns to see when it would slide out. It was a LOT easier to provoke oversteer with the fresh tires up front. The back tires weren't worn out or even close to bald either.

So generally if you put the new tires up front I'd watch your ass.

(this was with the FWD integra, not the S2000).

5/29/2009 7:27:58 PM

Quote :

"false. good tires (good tread depth) should be up front to handle hydroplaning. your average car at average speed won't be understeering or oversteering, but it sure will hydroplane. "

5/29/2009 7:47:06 PM

I've been told I do this wrong, but fuck it. :Grabs Flame Suit:


On the RWD Porsche, 2 new tires on front, front tires rotated to the back. I only buy directional because that's how I roll. When the rear tires are worn out, the front ones are generally still 90-95% new. To me, this is ideal because I always have new tires on the front for maximum traction braking, steering/hydroplaning. Also, when I need to replace the tires in the rear, they are already broken in. This is one reason why I like RWD setup vehicles with non-staggered rims. This may not apply to your RWD vehicle if your rear rims/tires are different sizes from your fronts. (lol this reminds me of the time an M3 owner walked in and wanted his tires rotated and the guys at NTB told him that he couldn't. He got pissed and said do it anyways because he paid for free alignments and rotations and wanted them rotated... He didn't understand what "staggered rims" were and claimed that they were rotated before...)

On the FWD MX-3, I throw the new tires on the rear (although this round I want to buy a complete set of stiff as shit sidewall tires , so the rears were swapped with bald front tires and I'm waiting for the front set to wear out too.). Similar ideology as RWD in the fact that since these tires are trailing, they experience almost no wear and tear. Thus when it's time to replace the front tires with new ones, I rotate the ones from the rear (with about 90-95% tread remaining) to the front and buy two more for the rears. Granted, this is a bit more dangerous if you don't pay attention and you let your all-in-one drive/steering tires get bald. But I keep up with the maintenance meticulously, so I'm not worried about those risks.

This system works for me. If you've got AWD, fuck it, you're just going to have to replace them in sets of 4 I suppose.



[Edited on May 29, 2009 at 9:08 PM. Reason : .]

5/29/2009 9:02:57 PM

wrong. best tires go on front.

5/30/2009 1:15:18 AM

how about your rotate your tires properly. You buy all four tires at once, but since you rotate them, you buy them half as often.

5/30/2009 3:31:52 AM

Quote :

"your average car at average speed won't be understeering or oversteering, but it sure will hydroplane."

Um, yes, but when hydroplaning, the location of the worn tires determines whether it will be understeering or oversteering.

Don't listen to these idiots. Assuming the worn ones still have plenty of tread on them, put them on the front.

These demonstrations show how dangerous having worn tires on the back is in the wet:

http://www.purigen98.com/Research.htm

Quote :

"The second demonstration used front-drive Toyota Camrys, again on a wet track but this time on an oval. One car had new tires on the back, and tires that were 50% worn on the front. The second car had new tires on the front, and tires that were 50% worn on the back. We started in the car with new tires on the back. Once up to speed (about 90 km/h) the front of the car started to lose traction. You could feel the front-end slide as the tires with 50% wear began to hydroplane. However, this was easily remedied, by taking your foot off the gas, letting the car slow down a little to regain traction, then getting back up to speed. None of our group lost control of the car with the new tires on the rear of the car. The second car had the new tires on the front, which is perhaps where you'd think to put them if yours is a front-drive car. Get more traction, right? Au contraire! Most of us couldn't get to 90 km/h because the back-end of the car would lose traction and violently slide around. Everyone went off the track, typically backwards."

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=52

Quote :

"The ability to sense and control predictable understeer with the new tires on the rear and the helplessness in trying to control the surprising oversteer with the new tires on the front was emphatically proven."

Now, having the worn tires in the front would probably result in increased braking distance in wet, however since the rear tires are less likely to lock up, it would increase stability under braking.



[Edited on May 30, 2009 at 4:01 AM. Reason : .]

5/30/2009 3:43:12 AM

Did not read thread, the answer is REAR

5/30/2009 8:56:19 AM

Quote :

"Did not read thread, the answer is REAR"

+1

5/30/2009 9:29:28 AM

meant to say rear. my bad.
mounted on front

mounted on rear


[Edited on May 30, 2009 at 9:55 AM. Reason : lol]

5/30/2009 9:54:27 AM

YOU'RE ALL WRONG

BEST TIRES ON THE LEFT

5/30/2009 10:00:06 AM

naw, right side for more one tire fire life

5/30/2009 10:12:18 AM

the ratio of my hydroplaning experience of going straight or turning is about 100:1. If you're going straight, the rears won't hydroplane as the fronts have already cut a groove. I say that if you're oversteering on bald rear tires, you're going too damn fast in the rain.

5/30/2009 11:25:52 AM

Rear. people who wreck their shit in the rain often have the back end go out first, regardless of the driven wheels

5/30/2009 11:37:45 AM

put one in the front and one in the rear

get the best of both worlds

5/30/2009 11:50:05 AM

I'd have to say rear...and totally from experience, I've learned this. My '84 Celica GTS (RWD, mind you, with the 22RE and IRS) would spin quicker than hell in the wet. I ended up ass-backwards planted in a ditch TWICE with that car. Not even driving aggressively...

5/30/2009 11:53:35 AM

^exactly my thoughts/experience. totally depends on the vehicle's weight, drivetrain, power, etc. if i HAD to pick a general rule though, i would say the good tires always belong on the drive wheels. i've spent enough time in the rain on drag radials and other bald rear tires to know that a rwd's ass will start trying to pass the front in a real hurry even with minimal throttle input. on the other end of the spectrum, i've owned/driven enough fwd's with bad front tires to know that in a straight line the front end can break loose and cause the vehicle to dart left or right. when turning, just the slightest bit of excess throttle can put you into a quick and decided understeer. as power and tire width increase in relation to vehicle weight in any vehicle, it just gets worse.

^^assuming we're talking about conventional open differential vehicles, that actually does make the most sense from a technical/theoretical point of view. having one good tire at each end "should" eliminate the possibility of overpowering both tires on a given axle at once. it would also curb any transitional oversteer/understeer as well.

in regards to the bit in the OP about oversteer being more difficult to control that understeer, i would hardly consider that to be a rule either. assuming we're talking about 99% of ignorant drivers, i would say oversteer is a much better scenario. the problem isn't so much the initial type of control loss, it's the reaction to it. what do most drivers do in such a panic situation? they jerk the wheel the opposite way, stand on the brakes, and freeze up hanging on for dear life. in an oversteer, even with the tires locked up, steering input is still somewhat effective and generally you'll continue going straight (maybe sliding sideways though, lol) if not back the other way some. the same knee jerk reaction in an understeer doesn't get you a damn thing except going straight as an arrow in the direction of the vehicle's momentum. combine that with the fact that oversteer is almost always happening in a turn and disaster is nearly certain. no amount of steering input is going to change your course with the tires locked up. finally, for the few that do manage to recover from an understeer, their momentary success is almost always immediately shattered by oversteer due to over correction. then, they're right back headed in the original direction of the understeer in worse shape.

all that said, i can agree for an EXPERIENCED driver who doesn't panic, that it's usually going to be a lot easier to recover from understeer. stay just off the braking threshold, steering input about 50-75% of the degrees towards the direction you want, and return to center just as you feel the vehicle transition. the issue with with properly recovering from oversteer, even for good drivers, is getting used to anticipating and accounting for the violent directional changes (momentum) of the vehicle's mass. there's a fine line between just enough to bring the vehicle back in line and too much. especially before you learn how to use brake/throttle input to control things in conjuction with steering.

5/30/2009 10:36:48 PM

That's it. Ivan, your new title from here on out is now:

DK

5/30/2009 11:32:59 PM

^^no way.

Why do ALL manufactures design 98% of their cars to understeer at the limit if its harder to control?

Its simple. If you're in a turn, oh shit i'm going too fast, i'm not gonna make it. What does 80% of the population do? Hit the brakes and turn harder. What does this do? Spin the car because the weight as shifted to the front unloading the rears which are now free to go. Designing in understeer combats this and helps the car simply plow and come to a stop instead of spin. The 80% reaction is much safer in an understeer situation, hitting the brakes puts weight on the front thus giving them more traction. Plowing straight due to too much steering input is much safer than spinning. A plowing car still has four wheels (well at least 2 wheels plus 2*cos(steering angle)) of braking traction due to ABS. A spinning car has nothing (ABS doesn't work if the tires are going sideways). Add to the fact that a spinning car can be very unpredictable both for the driver and for other traffic on the road.. its a disaster.

5/31/2009 11:14:07 AM

haha, manufacturers don't purposely design in understeer. among other things, it's merely a byproduct of basic physics, suspension/braking geometry, and economics. simply put, optimal handling dynamics take somewhat of a back seat to things like comfort, tire wear, and production costs. that's kind of beside the point though. whatever the reason behind it is, i don't think anyone will argue against that the majority of vehicles out there will understeer vs. oversteer.

as for more weight on the front tires helping things, that's just silly. any weight transferred to the front tires (like you even said) is weight lost from the rear tires. the overall force distributed among the 4 tires remains the same any way you look at it. mass isn't created and gravity isn't increased just because you hit the brakes. as for the increase in weight helping traction in turning, you're assuming a couple of major factors to be true (unlikely):

1. that the tires are rotating enough to allow that traction to initiate a change in direction. unfortunately, this usually just doesn't happen. even most modern abs systems won't allow a tire that's turned to spin enough at a fast enough rpm to help anything. only the most sophisticated systems will allow you to stand all over the brake pedal and steer out of a slide. snow/ice/mud does a great job of magnifying this.

2. that even IF the brake don't have the tires locked up, that the vehicle is even able to make use of the extra force on the front wheels. lets not forget things like the coefficient of friction, bias, etc.

finally, i never said that understeer was harder to control. in fact, i said that i think it's easier to control/recover from ASSUMING you have half a clue of how to drive. a retard isn't going to control either one though...

6/1/2009 5:42:04 AM

it's REAR, for the reasons mentioned above about hydroplaning...

[/thread]

6/1/2009 11:04:25 AM

Just b/c tires lose grip on a wet road doesn't mean they hydroplanned. You can lose grip by hydroplanning but you don't hydroplan every time you lose grip.

I'm mentioning this so we don't confuse any n00bs looking around in here.

6/1/2009 11:55:44 AM

Quote :

"haha, manufacturers don't purposely design in understeer. among other things, it's merely a byproduct of basic physics, suspension/braking geometry, and economics. simply put, optimal handling dynamics take somewhat of a back seat to things like comfort, tire wear, and production costs. that's kind of beside the point though. whatever the reason behind it is, i don't think anyone will argue against that the majority of vehicles out there will understeer vs. oversteer. "

false. vehicles are designed to be safe at the limit. understeer is safe. vehicles are designed to understeer. I've talked to Bosch engineers about this.

Quote :

" as for more weight on the front tires helping things, that's just silly. any weight transferred to the front tires (like you even said) is weight lost from the rear tires. the overall force distributed among the 4 tires remains the same any way you look at it. mass isn't created and gravity isn't increased just because you hit the brakes. "

Who said any of that bullshit? You're making crap up. I'm VERY well aware of vehicle dynamics. I'm not God's gift to driving, but i am an Advanced HPDE student and i've run several time trials and done well. In addition to that, i own several books on vehicle dynamics because i'm interested in that. I even applied for and got a job at Bosch in their Chassis Controls group. The 3 interviews were nothing but discussions of vehicle dynamics. I got a job offer.

Quote :

" as for the increase in weight helping traction in turning, you're assuming a couple of major factors to be true (unlikely): 1. that the tires are rotating enough to allow that traction to initiate a change in direction. unfortunately, this usually just doesn't happen. even most modern abs systems won't allow a tire that's turned to spin enough at a fast enough rpm to help anything. only the most sophisticated systems will allow you to stand all over the brake pedal and steer out of a slide. snow/ice/mud does a great job of magnifying this. "

This is false. ABS helps a LOT. Its not perfect, but its a night and day difference in steerability under braking. Regardless, having more weight on the front tires while turning increases grip.

Quote :

" 2. that even IF the brake don't have the tires locked up, that the vehicle is even able to make use of the extra force on the front wheels. lets not forget things like the coefficient of friction, bias, etc. "

What is your point here? random words? More weight WILL increase the grip of the tires. This isn't voodoo, its a law of physics. Increased grip doesn't mean the tires WILL bite and grip and turn if the increased grip level still isn't enough to initiate the turn.

Quote :

" finally, i never said that understeer was harder to control. in fact, i said that i think it's easier to control/recover from ASSUMING you have half a clue of how to drive. a retard isn't going to control either one though..."

Eh.. sort of agree. Understeer is "easier" to control because most people's knee jerk reactions to a situation (brakes + steering) are much more ok in an understeer situation than oversteer. Its not like they turn into pros while in an understeer situation, they simply coincidentally do the right thing.

Have you ever even been on a skid pad? this is kindergarten stuff here...

6/1/2009 2:09:10 PM

^^ of course, but hydroplaning happens a lot more often under normal "safe" driving conditions. And since we're talking about bald tires, then its about 100x more likely.

slick tires will grip a wet road better than treaded ones if there is no standing water, maximum contact patch area. You only need treads to flush standing water to prevent hydroplaning.

If you lose control WITHOUT hydroplaning in the rain, you did something stupid.

6/1/2009 2:14:14 PM

looks like we have a resident Automotive Engineer on our hands

Quote :

"slick tires will grip a wet road better than treaded ones if there is no standing water, maximum contact patch area. You only need treads to flush standing water to prevent hydroplaning. "

so what constitutes a wet road with no standing water? a wet road has to ahve some appreciable amount of water on it... else it wouldnt be wet. If that's the case, wouldnt it be too slick for "slicks"? Or are there other factors left out of the discussion, that are assumed with your statement?




and another thing:

Quote :

"I'm not God's gift to driving, but i am an Advanced HPDE student and i've run several time trials and done well. In addition to that, i own several books on vehicle dynamics because i'm interested in that. I even applied for and got a job at Bosch in their Chassis Controls group. The 3 interviews were nothing but discussions of vehicle dynamics. I got a job offer."

congratulations, I too own automotive books

[Edited on June 1, 2009 at 2:55 PM. Reason : -]

6/1/2009 2:45:21 PM

Quote :

"More weight WILL increase the grip of the tires."

Truth.

I mean, basically, increasing the normal force between the tire and the pavement will increase the grip via coefficient of kinetic friction. This is physics 101 shit. Really?

6/1/2009 2:54:45 PM

wet as in damp, no standing water. no pools, no puddles.

Watch an F1 race. If the track is just damp, they'll go out on soft slicks. if it starts to rain they'll move to intermediates (shallow tread), then if it pours and they get lots of pooling they'll go to full rains with deep grooves. the tread depth should be just deep/wide enough to evacuate the standing water.

The one time i seriously spun off track and nailed a tire wall was when it was wet and i was on treaded tires. went back out on on my rcomps and it was easy as pie. lesson learned the hard way.

6/1/2009 2:57:00 PM

Quote :

"^^ of course, but hydroplaning happens a lot more often under normal "safe" driving conditions. And since we're talking about bald tires, then its about 100x more likely. slick tires will grip a wet road better than treaded ones if there is no standing water, maximum contact patch area. You only need treads to flush standing water to prevent hydroplaning. If you lose control WITHOUT hydroplaning in the rain, you did something stupid."

Well yes, but i'm pointing it out b/c its a pet peeve of mine when people say they hydroplanned whenever they lose control on a wet road. When in fact the coefficient of friction has been reduced by the water (and probably any oil residue on the road) and they were just driving too fast.

And seriously, if anyone wants to drive my car on a damp road it doesn't take a lot to see how much more unstable it is b/c the good tires are on the front

6/1/2009 3:30:06 PM

^ What are you some kind of drift king in your honda now?

6/1/2009 3:40:45 PM

I completely agree that the coeff of friction is much less on a wet road than a dry road and that hydroplaning (over standing water) and slipping on a wet/damp road are two different things.

6/1/2009 3:41:55 PM

Quote :

"Best Tires in Front or Back? "

DANNY CARE TO ANSWER THE FUCKING QUESTION?

6/1/2009 4:04:05 PM

I'm sticking to keeping the good threaded tires up front.

Tread's only purpose (on pavement) is to evacuate standing water. Therefore hydroplaning is the only threat that treads can help with. So if we wish to combat hydroplaning, we need the good tires up front to evacuate standing water. The rears can follow in the valley of waterlessness (you know what i mean, you see these behind cars on the highway) behind the front.

The "put em on the rear" argument is flawed because it implies that the treads will provide more grip on a wet surface than a slick tire which is false assumign there is no standing water. If there is standing water, then i still think it extremely unlikely that the rears could hydroplane without the fronts hydroplaning first because even while turning, the rears follow a good bit in the path of the fronts.

***Now by a bald/slick tire i mean a still decent tire. If its corded or 10 years old and hard a rock it won't grip shit of course

6/1/2009 5:58:37 PM

Quote :

"I'm sticking to keeping the good threaded tires up front. "

Watch the video at the bottom of the page, and read the two links I posted above.

http://www.michelinman.com/tire-care/tire-saving-tips/replacement-questions/

It is demonstrably better to have the new tires on the rear. Every reputable source will tell you that. Your argument is not based on anything but flawed intuition.

6/1/2009 6:30:57 PM

Good tires on the back, no question.

But if you don't mind keeping an eye out for the occasional oversteer situation, then do whatever you want.

6/1/2009 7:28:48 PM

Wow, that is pretty interesting. I guess the rears can hydroplane a good bit even with good fronts. The point about being able to feel the hydroplaning of the front tires through the steering wheel is also good. M3 ftw.

Ok, i'll stand corrected on my front/rear theory. I was trying to think it through. I guess google could have helped.

I stand firm on my general vehicle dynamics for vehicles with four equal tires, though

6/1/2009 7:34:45 PM

Quote :

"hydroplaning of the front tires through the steering wheel"

I've felt that before (going down wade ave no less). Quite unnerving. It's a much different sensation than just sliding. Almost like I felt like someone picked up the front end of the car a little bit and the car was gliding on butter. Anyways, fortunately for me, I guess I was just at the threshold so I just got off the gas and the car slowed down, nothing dramatic happened. Interesting sensation.

[Edited on June 1, 2009 at 8:38 PM. Reason : .]

6/1/2009 8:34:41 PM

RMA recommends rear. They've spent buttloads of money to determine this, so don't think too hard about it.


[Edited on June 1, 2009 at 10:14 PM. Reason : asdf.]

6/1/2009 10:14:09 PM

the airplane takes off

6/1/2009 10:31:24 PM

so that's settled

6/2/2009 8:56:50 AM

Quote :

"false. vehicles are designed to be safe at the limit. understeer is safe. vehicles are designed to understeer. I've talked to Bosch engineers about this."

uh, bosch? as in the electronics company? as in the company that merely provides a limited amount of parts and controls for vehicles? since when did they start making executive decisions about manufacturer's designs? you're talking out of your ass here. i'm sure every engineer would love to believe they really have that kind of influence over the companies they work for, and we as consumers would like to believe that every product made only has our best interests at heart in terms of safety. unfortunately, both are entirely untrue. maybe next time you should talk to people that actually make real decisions. again, i'm not denying that most vehicles understeer. the reasons behind it have very little to do with what you've posted, though.

you're also severely contradicting your own arguments. if vehicles are designed to understeer, why are you being so adamant about things like weight transfer?

Quote :

"Who said any of that bullshit? You're making crap up."

you did. i'll trust you can go back and re read where you specifically mentioned weight shifting to the front tires unloading the rears.

Quote :

"I'm VERY well aware of vehicle dynamics. I'm not God's gift to driving, but i am an Advanced HPDE student and i've run several time trials and done well. In addition to that, i own several books on vehicle dynamics because i'm interested in that. I even applied for and got a job at Bosch in their Chassis Controls group. The 3 interviews were nothing but discussions of vehicle dynamics. I got a job offer."

uh huh. i forgot the rest of us are fresh out of driver's ed, can barely read the newspaper, and have only received job offers from the local mcdonalds.

Quote :

"This is false. ABS helps a LOT. Its not perfect, but its a night and day difference in steerability under braking."

i don't even really know how to respond to statements like this. all i can offer is if you truly think this is the case, your real world experience is not nearly as impressive as you seem to think it is. the truth is that the number of abs systems out there that really shine in the situations we're talking about are few and far between. no doubt that number will increase and eventually become the majority as we move forward with modern systems though.

Quote :

"What is your point here? random words? More weight WILL increase the grip of the tires. This isn't voodoo, its a law of physics. Increased grip doesn't mean the tires WILL bite and grip and turn if the increased grip level still isn't enough to initiate the turn."

lol, certainly... must just be random words since you can't understand the point. it seems you're so focused on extra grip from weight transfer that you're completely ignoring other very important factors:

-weight transferred to the front tires is weight lost from the rear. no fucking shit more weight equals more traction, i'm pretty sure that as an avid drag racer i understand that better than most, but it also equals LESS traction on the rear tires which introduces another set of problems. while POTENTIAL steering grip might increase, overall braking traction remains the same or worse. i'd also like to point out that you've failed to mention lateral weight transfer, since we are talking about understeer/oversteer and all.

-there is a point where traction is exceeded, regardless of weight. tire compound, tire size, surface you're driving on, and the list goes on. on a related note, brakes can also reach the limit that they lack the ability to put to use any extra traction from the tires.

i'm not really sure what the source of your confusion here is? i'm not doubting your knowledge or expertise, but it seems to be a lack of looking at the big picture though. what i'm reading is you focusing on a very few, albeit important, relevant factors and tossing the rest out the window.

[Edited on June 2, 2009 at 11:37 PM. Reason : .]

6/2/2009 11:30:08 PM

Bosch's Vehicle Chassis Division is who designs the ABS, TC, and ESPs for 80% of cars on the road. They work with the vehicle manufactures to design these systems so that that meet the manufacturer's specs (feel, performance, safety, etc) and regulatory agencies specs.

This is a good book covering the very basics which i studied for the interviews: http://www.bentleypublishers.com/bosch/Bosch-TI-Driving-Stability-Syst.html

I don't know about everything, but the job i was applying for was an Applications Test Engineer. The job was to test drive cars and tweak all the parameters until they met spec and felt good. There is a lot of cooperation between Bosch and the OEs to get things all sorted. They travel to your testing grounds, you go to theirs, etc.

I never said Bosch dictates the manufacturer's design. I said the Bosch engineers mentioned that they do as a matter of fact. I would think they would know, they need to tweak (for example) the brake bias to the manufacturer's spec which is probably a pretty heavy front bias which is safest.

I'm not contradicting myself. Just because they're designed to tend toward understeer doesn't mean they always will every day in every situation. I know you know this.

I think you're confusing "ABS helping" with "ABS working perfectly".

Of course the rear lightens as the weight shifts forward... thats why its a weight "shift" or a weight "transfer".. I surely never said this wasn't the case. This is why braking (shifting weight forward) while oversteering is a bad... i know you know this, too.

Of course there is a point where traction is exceeded. Thats how i ended up getting pulled out of the tire wall...

I feel like we're miscommunicating. I don't know what you're arguing about.

6/3/2009 12:47:47 AM

Small correction/input; weight transfer away from even distribution always decreases total overall grip. This is because grip is proportional -but not directly- to weight on a tire, given all else equal. To increase grip, increase weight on a given tire, without increasing it's workload (mass in a turn) on it. If understeering this would mean in an ideal situation to open the wheel, easing off the gas/braking are other methods.
Ahmet -->survivor of multi flip on wet track 100+mph into wall accident. Rear end hydroplaned on a straight @VIR.

6/3/2009 2:45:13 AM

Tell me how mass in a turn changes again?

F = uN (Force = the coefficient of friction * the Normal force). Thats as directly proportional as it gets.

Just saying.


When did you flip into the wall? What car? Was that when you were instructing? Thats insane.

6/3/2009 12:13:43 PM

Mass is not easily changed, that was my point. However, some mass shift does happen, such as the play in motor mounts.

Tire traction increases proportionally to weight placed on the tire, but the traction gained is not a 1:1 gain by load. This is why lower weight is good for grip.

I was instructing a student. Doing ~110mph on the back straight. It was wet, but had stopped raining several laps prior. The rear end came around, and we hit the tire wall by the corner station backwards. The car did a complete end over, rolled 2x on it's side, almost came to a stop on the tires, then rolled again to land with the passenger side down. I occasionally have back/neck pain from it, the driver was hospitalized but in OK condition. He took several months to get full movement back on his left side after breaking a few bones. It was an e36 M3 that he ended up parting, and last I heard from him, he was building another e36 M3 track car. Seatbacks were broken, roof a bit collapsed, trunk lid lodged between the C pillars, etc. If I get bored I'll dig up some pictures.

6/3/2009 2:41:19 PM

drag slicks ftw

7/5/2009 6:14:41 PM

it depends, is it taking off a treadmill?

7/7/2009 3:45:41 PM

Put the crappy tires on the rear. They'll last longer that way unless you're trying to be Burt Reynolds or something.

7/7/2009 3:57:17 PM

somebody remind me which one is tight and which one is loose

[Edited on July 7, 2009 at 3:59 PM. Reason : sarcasm. plz don't flame me ]

7/7/2009 3:59:08 PM