FasterIsBetter

I'm going to order some Kumho V710's for my '03 Z06. I have a spare set of stock wheels, 17" fronts, 18" rears. I'm going to get the 315/35WR18's for the rear. Tire Rack lists two possible sizes for the fronts: 275/40WR17 or 295/40. I'm leaning toward the 295's, but wondering if there is any good reason to go with the 275's up front. These are primarily intended for track days/road racing type driving.

Too Tall Bob

I have run two different sizes of 710's on my car: Stock @ 275/17 f and 315/18 R with really good results on the stock Z06 rims. The car has just a slight hint of understeer (safer) but I went through front tires about 25% quicker than I did on the rears.

I am now running 315/18's on all four corners to eliminate understeer and so I can rotate tires front to back.

To run the 295's on the front, you would need a wider rim than the stock 9"x17" front, so why not go to a full 10"x18" all around and have the benefit of rotating all four corners? As a track tire with the 10"x18" up front, I have no problems until I turn the wheels to full lock, but how often do you need to do that at the track anyhow.

With the 315's up front the car has no problems with understeer at all and handles like a slot-car!

Also, be sure to heat-cycle those 710's for best results and wear!

And one last thing: Be sure and turn off your AH any time you are running tire sizes different from what comes stock or you'll go through alot of rear brake pads! (You shouldn't be running AH anyway!)

tigerdrvr

I've run the 295 on the stock 9.5" front rim for the last two years with very good results...in autocross. I've also run the 275, which was probably just as quick.
However, for track use, I'd go with the 275, no doubt. It just has better turn in characteristics and "feels" better. You can get away with the squirm of the 295 in lower speed autocross, in trade for more ultimate grip, but for road course I wouldn't want it.

wtknght1

I tested 275s, 295s, and 315s on the front of my T1 car at Mid Ohio before the 04 and 05 runoffs with very little difference. The 295s and 315s up front provide a bit more steering bite and braking power at the early part of the run (session), but toward the middle and end of the session/race, the rear tires were the ones that were suffering.

And the kicker to all of it was that despite the "feel", the lap times were nearly identical. I was more consistent running the 275s for the record. They have less rolling resistance and a lower total profile so there is less aero-resistance. And in a nit-picky thing, the 295s actually raise the front end more than the 275s or 315s so now you've inadvertently changed the rake of the car, which also changes the aerodynamics.

Also, there is NO one right answer here. Different tracks have different characteristics - understeer vs. oversteer...as do drivers as far as what they like and don't like.

For starters, I'd go with the 275s and see what you think. Then try the 295s and then the 315s and make your decision. One good test is worth 1000 opinions!!

FasterIsBetter

Much appreciated gang! I love this forum. Very useful input. I think I'm changing my opinion and opting for the 275's up front to start with, and see how the car handles. Since they will fit the stock rims effectively, it's probably the way to go, rather than investing in additional rims at this point. I'll see how it handles, and go from there.

Many thanks.




Steve

Too Tall Bob

You will REALLY like that 275f/315r combo, and as was said before, there really is very little difference between the different sizes as far as handling, but I like to rotate my tires around.

If you haven't already done so, be sure to get as much negative camber as possible and the Kumho's will love you for it. Best track tires I have ever tried!