hungryhippo

I tried a search, but only found information on race tires and it not being a good idea because of different compounds and temps.
But what about with street tires with a 100-200 treadwear? I figure they will be more similar. I'm running matching tires now, but if I can have different front and rear tires, it would help with my tire choices and save a couple hundred dollars per set. Thanks in advance.

el es tu

the issues have to do with sidewalls as well, the stiffness and dynamics will be different
that said, I run two different types of street tires on my c6 (bfg something up front and the low level emts in the rear) since im waiting to upgrade the wheels tire and brakes at once. Its not ideal, but I run the car up to 1+g just about every time i drive it. max speed ive been on them is 180 and didnt have any high speed stability issues.

Differnt tires are doable, but youll be better off with the same model tires front and rear.

what wheels/tires are you looking into and what type of vette is this for?

hungryhippo

It's a base C6 and I want to keep the same diameters as stock. I want to try a 275/35-18 NT05 up front and 285/35-19 RE-11 in rear.

avizandum

What will you be doing with the car?

My .02 - mixing and matching for DD and AutoX, no issue; just learn to drive the car. On the track where heat will change things and at different rates, not a good idea. Street tires will not be more similar, if anything, more different.

FWIW on the front tire size - I've run Kuhmo XSs in the front in 245 and 275 and the 275s were faster, aso have run 245 and 275 in Dunlop Star Specs and the 275s were slower.

My experience is that XSs 275/285 is an optimal choice for C6s, but beware in the rain once they've worn. I had the best success with that combo before crossing over to Hoosiers.

No experience with Nittos... a friend of mine who's a good and extremely consistent driver (AutoX) tried Nittos and did not care for them on his C5Z06.

longdaddy

you can certainly do it, but you need to figure out the dynamics of how they respond to heat/pressure build up or any other traction "conditions" - rain etc.

if this is for track use, you probably want to take it easy at first and be concious of what the response is when they start overheating

for example (my experience): NT05s start with good traction when cold, get into the sweet spot within a few laps, as the sidewall "firms up", then gradually lose the ability to maintain small slip angles over about 10 minutes, then start becoming pretty unpredictable if I keep pushing it. they also change in "feel" as well as sound, as they go through this process.

I do not have RE11 experience, but I am sure they have their own unique way of going through such a cycle.

you would have to learn both, and how they interact together, and how that affects the car's response to what you are doing.

if you run at a safe track and willing to invest into learning one extra aspect of tire management that the rest of us do not have to deal with, why not. you would probably come out a better driver.

having said all that, I would not do it just to save money if I needed to buy 4 new tires anyway. if you are having selection issues with exact sizes, why not just get slightly narrower/wider tires than what's recommended for your wheels?

justkickin

Like others have said, if it is just the street, likely won't matter. At the track it will, depending how hard you want to push it. At 8/10s or less it likely won't matter.

I do disagree wit the one post about autox. There it will matter if you want to be half way competitive. The tires need to be able to heat up and get sticky real fast and equally. For one run at autox you can do 30+ turns (lots of heat). To get that many turns, you would need to do 2- 3 or more laps at most tracks.

Basically, depends what you are doing with the car and how hard you want to push it.

hungryhippo

This is for street and open track driving. Kumho XS is the only one that has both sizes, but I'd like to try something a little better in the rain next. Also I don't want to run tires any smaller in diameter than stock. I'll just keep my stock wheels and tires around for rain until more sizes are available.

justkickin

I hear ya on that one. On my C5 I run narrower thann stock RS3s, but the outside diameter is fine. Google a "tire size calculator" and get OD of your tires, then you can input alternate sizes and get that OD. As long as the OD of the two sizes is within 3-5% things will be fine.

RDnomorecobra

open track? I personally would not be comfortable mixing, unless you can truthfully tell yourself that you won't try to go past 7/10's or so like stated above.

longdaddy

kumho is a capable rain tire, in my experience. i doubt you will find anything that is significantly better in the wet that can still be driven hard at speed with predictable results, unless you go to dedicated rain racing tires.

brkntrxn

I have done it with street tires and R-comps. Mixing tire compounds and sizes is more drastic than air pressure changes and less expensive than suspension changes.

As long as you think of it as a tuning tool AND recognize the points made above about differences in sidewall stiffness and temperature variance, you will be fine.


-Kevin