Thanks to all for the information. I guess over the winter I'll be shopping for tires for the rear. This is a great fourm!!!


Tom Grance

 

Yes, I meant same tire diameter will cause a problem with the computer. But also tire width being the same may cause the car to be dangerously unbalanced since they are designed to have wider tires in the back than the front. Guess I didn't put that into words very well. My current project is a Z06 that someone put standard C5 wheels/tires on back, then spun it out and backed it into a light pole!

 

Well, after paying my christmas bills I'm ready to purchase rear tires. The goal of this change is to stop the traction control from coming on when it shouldn't. I have 275/35 18 all around mounted on 18" rims. From what I've learned here I need a wider tire as well as a larger diameter tire. From all the info I've gathered the best choice would be 305/40 18 if it will fit on the rims. Will it fit? If the 295/40 18 will correct the problem I'll go with them. Now where to buy them? The tires on it now are Kumho's.

 

Tom,

Can you give us some more specifics about your wheels, esp. concerning wheel width? If they're 18x9.5 (stock C5 rear wheel size), then a 305 is a big stretch. I use it for my race tires, but I wouldn't want to do that for the street.

If they're Z06 wheels (can't tell just by the style, Z06 repros can be had in stock C5 sizes), then a 305 will work just fine.

Another alternative you can go to is a smaller front tire. This does two things: it solves your Traction Control problem, and it also gives you a couple of replacement tires for your rears, for free!

Assuming stock C5 rear wheels up front, you should be able to go to a 255 series tire with no problems.

HTH, and have a good one,
Mike

 

For tire info check my post out:
http://forums.corvetteforum.com/show....php?t=1211751

 

I emailed the previous owner of my vet and he informed me the first owner put custom wheels on. I cannot get in touch with him to find out what they are. I have no idea why this guy put the same size tire all around. How can I determine what I have and the exact size.

 

Do you have pictures of the wheels?

The best way to measure the width without taking the tire off would be to measure the wheel width from the inside bead to the outside bead. This would probably get us close enough:

Look at the RIM WIDTH DIMENSION.
You could probably get a good approximation just by sticking a measuring tape between the spokes (hopefully you have enough area to stick a measuring tape through there.

Also, I know you said Kuhmo, but what is the exact name? I'd like to know if its a runflat type as well...

I'm working on some numbers right now...ill post up in a few minutes

EDIT:
OK - I am definitely agreeing with "robvuk" on this one.

Original Front Tire Height = 25.68"
Original Rear Tire Height = 26.66"

Current Tire Height = 25.57" (which is a great match for the front but not the rear)

New Rear Height with a 295/35/18 = 26.13"
New Rear Height with a 275/40/18 = Same as OEM which is 26.66"

If you like the width of the current tire in the rear and dont want to risk a too wide of a tire not fitting properly on the mystery wheels, go with the 275/40/18
If the current Kuhmos are runflats, try to keep with runflats...in other words, dont put non runflats in the rear and runflats in the front...or visaversa

Optimal would be to buy 4 new tires that way theres no mix and matching...but obviously the price is twice....

 

i have 18 all around on my 99 with smaller tires front. there is a thread from a very knowledgeabls guy on tires that you should read re wheel height compared to stock. i can get you the tire sizes i put on mine if you want because mine work great. new f1's. speed checked with gpa and was perfect on spedo. search tire size.

jim

 

i have 18 all around on my 99 with smaller tires front. ther is a thread from a very knowledgeabl guy on tires that you should read re wheel height compared to stock. i can get you the tire sizes i put on mine if you want because mine work great. new f1's. speed checked with gps and was perfect on spedo. search tire size.

jim

 

Well, an easy way to get an idea of the wheel width is to take a tape measure and measure the width from the inner lip to the outer lip. Good enough for what we're discussing.

HTH, and have a good one,
Mike

 

Just checked back in on this thread. Although it is preferrable to have the rear diameter larger than the front as long as your front and rear tires are the same diameter you will not have a problem. The only time you can get a problem is when the rear tires are smaller in diameter than the fronts. So you don't need to go and buy tires right now. I use the same diameter tires front and rear at speeds up to 150 mph on the track with no problem.
Bill

 

But don't you turn TC off on the track? Even if it does work, I would think equal diameter tires will lower the threshold and make it hyper sensitive.

 

Thanks guys for all your input. I measured the wheels and the bead width is 10". The over all tire diameter is 25". You can check out my wheel and tire pics here:

http://www.grancephoto.com/Temp/Vette.shtml

I'm new at this Corvette Ownership thing, so to as me what I like as far as tires, I only know the Kumho Escta Supra tires that are on it. Again, the reason I am doing this is becaues of the Traction Control problem. The problem does go away when I turn on Competive Mode. I guess this would defete the whole reason for having Traction Control.

 

Competetive mode turns off TC but leaves AH on. This proves 99% that it's a tire diameter problem. The size you have now (275/35/18) is fine for the front. I'd get some matching 295/35/18 for the rear. They should work just fine on the wheels you have and you can save the old ones to replace the fronts.

 

I just spoke to a sales person from Tire Rack. This guy tells me the 295/35 may be to big and rub the fender. His advice, I know he's a sales person, is to suck it up, his words, and replace all four with 255/40 front and 285/40 Rear. He also said the Kumho tires are a cheap tire and recomended buying a better tire. This isn't the direction I want to go. So I'll keep listening to you guys for a while longer.

 

Why would a 295 rub the fender??? That's the stock C5 Z06 tire size. I agree the Kumho's are cheap but it sounded like that's what you've been trying to do here. Save a few bucks.

 

I usually turn it off but sometimes I forget and find out it is on when it interferes at some point. Depending on how smooth I am this can be some time. On a road course you are not banging the shifter or sliding the car around as you would in an autocross and TC will allow a lot of leeway under the right conditions. When I have forgotten to turn it off when autocrossing it might kick in a little quicker with the equal diameter tires than when I am running the stockers but it is hard to tell since one set is sticky and the other is a street tire so will slide more.

Bill

 

Never listen to sales people. Always listen to fellow enthusiasts. Tell tirerack your buying them for a custom street rod. Good luck with your endeavor.

 

I think I found the mysterious Wheel brand. The first owner tells me he bought them off ebay from AFS. He put 18" all around because "it looked good". Should I try to buy a 17" wheel to match and return all to stock or buy a larger diameter tire for the back. Either way I'm going to spend the bucks.

 

Been there done that.
I have four sets of wheels and tires, two of the sets are Z16 wheels, one Z16 set has Yokohama tires in Z06 sizes the other Z16 set has Nitto RR2 on the front and BFG drag radials on the back. I had the drag radials on the back and inadvertantly put the 18" Yokohamas on the front.
All was cool until I drove on the interstate, when I would go up a grade the torque converter would disengage and 'traction control active' would appear on the DIC, I had to press the console button to clear.
Drove me crazy until I realized my mistake and put the 17" wheels on the front.
The front tires have to be smaller in diameter than the rears.