Do stretched tires compromise grip/handling?

[FunfGan]

^Winning.

[Apps]

If you are further interested in this topic I suggest you pick up some basic literature on vehicle dynamics or google cornering stiffness.

The sidewall flex that everyone else is talking about is parameterized by cornering stiffness in the tire world. What it describes is the rate at which the tire will produce lateral force. Physically this can be seen as the initial linear slope of slip angle vs. lateral force for a given tire. Many factors affect cornering stiffness and the "stretch" or angle of the sidewall is an important factor. In testing the cornering stiffness will continue to increase until the angle of the sidewall approaches that of the tread section.

Construction of the tire itself will contribute to the cornering stiffness and things like tread compound actually play a much more important roll than the sidewall stiffness. It's easy to understand as sidewall flex but this is just one part of the interaction. For instance the relaxation time of each material included in the tire will have an effect. The stiffness of the summit in bending and in shear will have a large effect. Even the size of the bead mounted to the rim will have an effect.

As everyone has stated before some "stretch" may be good. In fact ALMS teams use it as a balance and tuning parameter. Take a look at the Pratt & Miller C6R's they usually run a wheel larger than the measuring wheel up front.

At the control end for the driver it's down to the required response of the vehicle. A vehicle with higher cornering stiffness will respond faster to input but will also drop off quicker at the limit (unless this is countered by material choices). Actually changes in mechanical grip are negligible unless extreme differences in cornering stiffness are had.

In the case of every street tire it will most likely be perceived that handling has been improved with higher cornering stiffness (especially by gear-heads). Until you run the risk of unseating the tire or scrubing your wheels handling will improve with stretch (as others have stated before comfort will not).

As with anything you can have too much of a good thing...

[Wh33lhop]

It's really a horse a piece, and doesn't do all THAT much, But...

Stretching the tire takes up the sidewall flex it would normally have, resulting in a more rigid tire. Stretched tires have a lot less give, and are more likely to lose their grip in hard driving situations. But the other side with a straight wall, while having more flex and giving more feedback as to when it's going to lose grip with a more comfortable ride.

Unless you track it, you'll never really notice the instantaneous grip loss that can occur. But it will be less comfortable and more likely to bend/scuff a wheel.

Now, mind you, this is all dependent on amount of stretch too. A mild stretch can be a good thing for spirited driving with a tire that doesn't have a reinforced sidewall. But, those tend not to have the best grip out there anyways.

There are those that will argue tooth and nail that it makes zero difference.. It's the extreme examples that are the worst. But a little stretch never hurt anybody, and is common out on the track when you can't afford higher performing ones.

My thought is, and always has been. Use a wider wheel for what it was intended. A wider tire

Quoted for truth, every single word in this post.

[Holland]

drifting isn't the same thing as tracking, when you're purposely trying to slide the car..

Lol, that's why they stretch them ridiculously on purpose, and as Yoshi stated, they are technically on a track, not racing, but on a track. My point was more or less that you can, but it probably won't be beneficial. Also that the fact that they are driven hard on, clever word usage, shows that it isn't that dangerous to run them. Not my style but not really hating either.

[CHIF8008]

rims- not the rubber
tire- not the metal
wheels-rubber and tire together as a combo

lol

[grippymonkey]

^ waste of time.. we all know what people are saying when they use the slang term for wheels... aka RIMS

[agent]

They are wheels, not "rims". Rims are the outer section of the wheel...

QFT

wheel
Noun: A circular object that revolves on an axle and is fixed below a vehicle or other object to enable it to move over the ground.

rim
Noun: The outer circle of a wheel, attached to the hub by spokes.

hub
Noun: The central part of a wheel, rotating on or with the axle, and from which the spokes radiate.

tire
Noun: A rubber covering, typically inflated or surrounding an inflated inner tube, placed around a wheel to form a soft contact with the road.

[shiboujin]

I'm not even sure what this thread is about anymore.

I found out yesterday my 245s are too meaty in the rear to tuck even with rolled fenders. Although, I'd fit them if I would take off the 1 inch spacers. But then my front track would be 2.5" wider on EACH SIDE than my rear.

[z31maniac]

Whats this jibba jabba

On a productive note, has anyone read the recent mx5 tire comparo in grm?

Yeah, couldn't believe the way the RS-3 hammered the other tires.

[FunfGan]

Hahahah. Sig'd ^ . And anyway, is that so? My point is not that theyre "chunky" in their width, but in their height. Most people envision "stretch tires" as tiny little rubberbands, I went with a lil taller of a tire. Looks old school jdm tyte yo.

[shiboujin]

Ever seen a fat woman? Stretch marks AND meat.

[325ix]

theyre 205/50R15. Yea, I too love the meaty stretch haha. But Johny Cash, where were you going w/ that?

Meaty and stretch are two opposite things last time I checked.

[shiboujin]

You just want to argue with me today :) Despite the fact I'm agreeing with you.

My point is, if you have 195/70/14s as your ONLY tire choice. I'd rather have them stretched than not. It would help you grip int hat situation. In reality, this isn't true and for grip driving, there is virtually no reason to stretch.

[nando]

because you're not trying to grip. you're doing the exact opposite.

[shiboujin]

drifting isn't the same thing as tracking, when you're purposely trying to slide the car..

Why isn't it? You do it on a track :)

I run stretched 195s on a 15x8. Not a huge stretch in most cases but meh. I run it specifically for less sidewall flex.

We are really splitting hares here (lol). a stretched 195 as opposed to a non stretch 195 will probably grip better if you're dealing with like a 70 sidewall. When you get to bigger diameter rims where sidewalls aren't that tall, it doesn't make as much of a difference. Floppy sidewalls make cars shimmy in corners and not retain grip well. The stretch isn't what effects it, the sidewall does. You shouldn't be using 60-70 sidewalls on a track anyway. But if you have to, stretch em. that's probably the only time it's worth it. Even then, you've dumped so much money into rims to stretch them on, get good tires to begin with.

TL;DR get 275s with no stretch, be happy.