bselltiz

Running my stock C6 rims with Toyo R888 for HPDE 3 & 4.

Toyo says 245/40 is recommended for the front over the wider 255/35 which they say will also work.

Their tech told me that having a wider rim / narrower tire will provide better traction than a narrower rim / wider tire.

Who knows for sure??

Thanks!

haljensen

Tires are designed to "fit" a particular wheel size, they will work on other wheel sizes but are at their best on the dedicated size wheel.

If you are changing tire sizes on a C6 remember that there is a narrow window for front/rear tire size differences.

old motorhead

Unless the tire doesn't fit the rim properly, the wider tire wins.

bselltiz

old motorhead - so how do we define 'properly'?
I have actually run the next size up a couple of times and been fine, even though Toyo said no good. Was I loosing traction? Was I over heating the tire? Was I getting better grip? I really don't know.

old motorhead

Ahhhhhh shoot. Maybe you need to define that yourself a little bit. Not being a smartass, but a lot of that depends on what you're expecting in relation to what you're running now tire wise. Lots of variables. Maybe visit the Autocrossing and road racing page. Lots of sharp cookies there

SK360

I'd say listen to the guy who works for a tire company?

truckplay

make sure the contact patch of the tread is even with the bead on the wheel. try to minimize sidewall deflection (bulge in the sidewall) tires specs will tell you the recommended width of wheels to be used. tread compound will dictate level of traction.

BEZ06

And it looks like the 255/35 will fit just fine on a stock 18x8-1/2" wheel. Take look at the Toyo R888 specs on the Tire Rack site (click on the "specs" tab and scroll down to the tire sizes you're interested in):

http://www.tirerack.com/tires/tires....el=Proxes+R888


You can see that the top of one column is labeled "rim width range". The 245/40-18 is designed for a 8-9.5" wide wheel, and the 255/35-18 is designed for a 8.5-10" wide wheel.

So.....with the 255/35 you'll be on minimum side of the range, but it looks like an acceptable wheel/tire combination.

That tire has 0.6" less diameter than the OE size tire, but I don't think that will give you a problem - if anything you may just get a "drag control active" message when you lift off the accelerator, but that shouldn't be a big problem, although you may not be getting max engine braking.

Bob

EyeMaster

There's more to it than width of tire and rim. It also depends on what you want as a driver. It's also hard to judge on a Corvette when compared to a lighter more direct feel car, such as real formula cars, or even a Miata (where I had my experiences).

If the tire width is exactly the same as the rim width, your steering feel will not be as precise as if the tire was slightly inside the rim width. The side loads will make the tire deflect, or in other words, when the rim turns, the tire will be slightly delayed, in turn making the steering feel delayed. This gets amplified the wider the tire gets when compared to the rim. To some people, having more technical grip is not as preferable to having great steering response / feel. Add to this that you're adding weight at each corner because of the tire width.

Another aspect would be how the tire wears and how it heats up. I don't think it applies in this case because the difference is so small. But where the diff would be bigger, then you have lots of compromises to make. Some will put much lower pressure for better grip, but then the tire wears unevenly, sometimes making a w pattern of wear. The lower pressure, wider tire = more grip but less feel again.

All this was for nothing. 245 or 255 is not much of a difference. I doubt you would notice anything different. Try both, with the same type of tire, and let us know what you think.

Thunder8

After selling performance tires for a few years, this is the most accurate info, IMO. You may not get a very noticeable difference in handling per se, but you may get the "look" your after.

On my C6, I've ran the 255 in front and 305's out back, without an issue. I liked the way the 305's looked from the rear, that was my reason. I "think" I was able to launch better, but that could've been a placebo effect, lol.

bselltiz

EyeMaster - good info.
Thank you to ALL for your feedback. I think in the end I am over analyzing this. Its not like I am some pro racer, and to be honest all these variables are giving me a headache.
Corvette Forum rocks as usual, as for me - I'm just gonna go have some fun on the track and worry less about my tire width.

EyeMaster

Thanks.

Unless people are racing for money, I always find people overthink things! Costs involved in making things near perfect is just too high if the return is just fun. Fun is cheap.