Tire Decision

The kit is due to be shipped from Factory Five in about six days. One of the first elements of the build is to get the chassis up on wheels so that it can be moved around. The goal is to have it mobile by the end of July. I believe that is doable (and I could be a 100% wrong!).

This means the tires need to be purchased sometime in the next six weeks. As of this writing it is June 3, I probably need to get tires ordered by June 17. This is where previous build decisions have an impact on the tire decision. The stock tire sizes for a C5 Corvette are 245/45 - 17 (front) and 275/40 - 18 (rear). If I were going with the stock donor, then I would use the donor wheels and purchase matching tire sizes.

One of my decisions early on is based on the whoa and go concept. The GTM (regardless of the engine) has plenty of go. It is fast. It is sleek. It will rumble and growl. It looks like it is breaking the speed limit sitting still. I have an LS1 in my C5 (albeit, with a Hurricane cold air intake, Corsa Pace Car Sport Exhaust with Tiger Shark Tips and a cross over pipe) and she pops, rumbles and growls. There is plenty of power for the C5. A GTM at 800 to 1000 pounds lighter will be that much quicker. However, my buddy Brian pointed out that while I had the Go figured out, what about the Whoa? The Whoa comes in the form of the Big brake Upgrade.


The big brake upgrade requires 18 inch wheels front and rear. This is a departure from the stock C5 configuration. To accommodate the big brakes, I needed to purchase bigger wheels. I purchased Forgestar F14 wheels. These are the same wheels featured in the Factory Five catalog. These changes are within spec for the GTM. The monster LS7 power car that Factory Five built and that was featured in Car & Driver had the big brake upgrade and the larger wheels.


Tire sizes jump to 245/40 - 18 (front) and all the way to monster 335/30 - 18 (rear). The rear tires are a street legal drag radial. An alternate size for the rear tires is 295/35 - 18. Selection for the largest tire size is extremely limited and cost is quite high. The intent for my GTM is street use (granted I'll be the leanest, meanest on the block - Dodge Vipers beware!) When I drop down from the 335 to the 295 width, my tire selection goes up and my costs come down.

The OEM tire for C5 Corvettes is the Goodyear F1 Eagle run flats. These are noisy tires. They tend to drone on long trips. I would be hard pressed to point out a C5 in the Myrtle Beach Corvette Club that hasn't upgraded/replaced the Goodyear tires. Most people migrate to the Michelin Pilot Sport PS2 or PS3. This seems a safe and popular choice. I bounced this off my buddy Brian and heard quite the horror story about his Michelin Tires. The approximate cost for these tires is $1510 ($320 for front, $435 for rear).

Factory Five recommends Toyo Proxes 1. From everything I read on these tires, they are real good, a tad bit noisy and tread life seems a bit short. There is a real shortage of dealers selling these tires. The lack of a good dealer network is a deal killer. The approximate cost for these tires is  $1272 ($255 for front, $381 for rear).

About a year and a half ago, I replaced the tires on my Boxster with Continental Extreme Contact DW. What a difference these tires made! They were quiet. The grip the road. In the Boxster this is important, because I like to take sharp turns (testing the strut braces and Eibach performance sway bars - you know. Especially on Troy Lane!). These tires live up to their billing. I really like these tires and I have experience with them. The problem is availability in the rear tire size. The approximate cost for these tires is  $? ($195 for front, $? for rear).

This winter I replaced the tires on the Corvette. I wanted to go with Nitto Invo, but I could not find them in the Myrtle Beach area, so I went with the NT555. These are good tires. They are quiet. They have a long tread life. They hold the road (and some of the roads along the Grand Strand leave a lot to be desired). The Invo is an asymmetrical tire (like the Continental Extreme Contact DW) and it is available in the sizes I need. The approximate cost for these tires is  $886 ($188 for front, $255 for rear).


I based my cost estimates at Tirerack. 


I am going with the Nitto Invo. I am impressed at the ride quality I get in the Corvette. I like the way she handles. The Invo is Nitto's premier performance tire.