So I have a couple questions about wheels for use at HPDE/PDX or any road racing events.

I am still at the beginning stages of road racing, and have a lot to learn yet about driving and making small changes to the car. My C5 is also very much a street car, but I am prepared to make changes that improve its abilities on the track as I progress with my skills as a driver.


I've currently got a set of chrome 5 spoke C5 wheels 17x9 in the front, 18x10.5 rears. Firstly, I realize that chrome wheels are heavier than a comparable aluminum set, but besides that fact do chrome wheels hold heat more than an aluminum or other material?

This past weekend, I went through a set of brake pads and was carrying a lot of temperature in my brakes/wheels which caused some fade when I didn't want it - I actually melted the rubber boots encasing the pistons in the rear calipers.

Obviously I need to cool my brakes better. In the front, I do have brake ducts that bring cool air in from the front bumper. I have drilled/slotted rotors all around, and I also think that if I get a more aggressive pad that I will be on the brakes less, and therefore using less energy and creating less heat. But alas, my question is about wheels.

What material wheel is best for dissipating heat? And is there a particular style of wheel that is better for heat reduction? ie, I've read somewhere that more spokes are better for cooling? Would Z06 wheels be considered "more spokes" and a performance upgrade to my 5 spoke chrome wheels?

Next question: I've been unable to find definitive information on the advantages/disadvantages to squaring up my wheels on all four corners. For example, if I were to get Z06 wheels, should I consider getting 18x10.5's all around? What are the advantages on the track of going to the same size wheel/tire all around. Are there any disadvantages? Particularly with every day driving? (rubbing up front from the bigger rim? etc.)

Any insight would be great! Thanks!

 

Most people use the Z06 speedline wheels on track events because they are pretty much the lightest ones available besides the magnesium wheels unless you want to spend some serious cash. The z06 wheels are wider than the magnesium wheels though, so I would still go with the z06 wheels. Lighter wheels will decrease brake fade quite a bit.

I would go with the 17's on the front. If you go with the same tire sizes all the way around, your active handling and traction control system will not work properly. The fronts should be at least 1/2" less in diameter. I can't speak for the fitment as far as rubbing goes with the 18's up front. Even if you could fit the 18's up front and you wanted the same tire size all around, the fender clearances would be drastically different front to back, and it would just look goofy.

 

You will get ah/abs codes if you go to 18 in the front and don't go to 19 in the rear, you must maintain the original 1" difference or suffer the consequences!

ps you will have the same problem if you change tire size without maintaing correct dia. difference
both of these problems are well documented!

 

Check out this thread. It's got tons of great info for aspiring track guys.

 

That's not true. The rim diameter is irrelevant as long as you maintain the original difference in the overall diameter of the tire. You would do this by getting a tire with a shorter sidewall. You can run the 18x10.5" z06 rims on the front with the right tire. I, and many others on the forum, have run a 275/35-18 on the front. The tires will be slightly stretched. The dimensions are nearly identical to the stock 265/40-17 used on Z06s and will not mess with ABS/AH. The rim itself rubs the control arm only at full lock... I'm talking power steering pump whining full lock. Fender rub is not an issue at any reasonable ride height. You can also run a 295/30-18 up front if you want a square tire setup to reduce some of the understeer, but I have no first-hand experience with that.

That said, there is no real reason to run an 18" rim up front unless you need clearance for larger brakes, or if you really want square tires.

 

Thanks.. I actually read this guys entire thread. It's excellent! I'm going thru and using his information like a reference book to guide me through this whole process of getting into tracking my car! Ill be taking all his recommendations into consideration for sure.

 

Actually, the faster you go the more brake you will use and the more heat you will make. Get rid of the drilled and slotted rotors as soon as you can, they will crack under any serious track use. As far as wheels, get to an 10.5 X 18 square set up as soon as possible. Try some TSWs for a start. Traction control is the only thing affected by diameter of the tires and you will have that turned off anyway. I run either 295/30/18 all the way around or 295/30s up front and 315/30s out back.. Have fun! See you at the track!

 

Can you - or anyone chime in - on your experience from switching to square tires on the track? Does it balance the car better? Improve under steer? Im just looking for an idea of what moving to 18s up front actually does for the handling of the car.
Thanks

 

It does balance the car better and it does it without increasing oversteer. When I switched I anticipated better turn in but I just assumed that would be at the expense of oversteer. Just not the case.

 

One of the main reasons going to a square set up is for rotation purposes. You will be able to rotate tires to any corner to get the most out of soft compound tires. Since the front tires edges wear more on the track (depends on your alignment also), having a square set up allows you to rotate front to rear to get all the life out of your tires.