Question of wheel size and brakes that'll fit........

I'm in the planning stages of building a GT40. One of the things that has come up is the wheel diameter. I'm thinking of building a car from Active Power Cars and they use Corvette C5/C6 suspension pieces and brakes.

I've seen that the factory size rotors are 12.6" on the front and 11.8" on the rear of a C5 Corvette. Would these fit in a 15" wheel or do I have to go to a 17" wheel? I believe what they sell is 17's.

I'm trying to build that car so that, at least from 20 ft., it looks as close to an original as possible. Car will be RHD with the shifter on the right. I know that when the clamshells are opened an informed person will recognize the car's not the real deal. I can't imagine ever even seeing a real one given their $$$$$$ value today. I like the look of having a sidewall in the tire vs a 17" wheel with the smaller sidewall and starting to look like an 05-06 Ford GT.
 
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That's kind of what I was figuring. Looks like it'll be the 17" diameter.

Another thing was rear flares. I've seen "stock", 2" and 4" flares available. Any comment on what's the difference other than the size of the rear tire. I do like the look of steam rollers out back.
 

Ian Anderson

Lifetime Supporter
Supporter
That's kind of what I was figuring. Looks like it'll be the 17" diameter.

Another thing was rear flares. I've seen "stock", 2" and 4" flares available. Any comment on what's the difference other than the size of the rear tire. I do like the look of steam rollers out back.
First search and find what width tyre you can get! Not sure about your regs over there but so,e of them are only S to T rated for speed, not much good if you want a safe ride

Ian
 

Julian

Lifetime Supporter
It depends on your wheel, but with cast repro 15" wheels I've found that maximum rotor diameter is 11.75".
Bob, can you recommend calipers that are an upgrade from the C4 Corvette that will work with those wheels and rotor?
 
First search and find what width tyre you can get! Not sure about your regs over there but so,e of them are only S to T rated for speed, not much good if you want a safe ride

Ian
This is the US. I'm pretty sure I can get anything I want, especially in the 17". And getting a speed rating of 149 isn't tough. But I know the 15" tires are getting harder to come by. But I'm pretty sure RCR has availability of Avon tires still.


L 75 mph 120 km/h
M 81 mph 130 km/h
N 87 mph 140km/h
P 93 mph 150 km/h
Q 99 mph 160 km/h
R 106 mph 170 km/h
S 112 mph 180 km/h
T 118 mph 190 km/h
U 124 mph 200 km/h
H 130 mph 210 km/h
V 149 mph 240 km/h

When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of vehicles that have extremely high top-speed capabilities.

W 168 mph 270 km/h
Y 186 mph 300 km/h

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.

225/50ZR16 in excess of 149 mph, 240 km/h
205/45ZR17 88W 168 mph, 270 km/h
285/35ZR19 99Y 186 mph, 300 km/h
 
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Terry Oxandale

Skinny Man
Supporter
I'm using the C4 rotors (~12") and Outlaw 3000 calipers. I could not put 15" wheels over them. Currently running 16" front, and 17" rear (due to street tire availability with the 345s). I did find a Wilwood bell (1.16" offset) and rotor (.810") combination that was within .040" of the OEM rotor, thus they interchanged very well if you choose not to go the OEM rotor route, or need some cheap street rotors that can easily be swapped for some track rotors.
 
I may be changing my plans here. I keep looking at pics of the cars and the more I look, the more having 17's make it look like a newer Ford GT. The 15's with more sidewall really gives the car that 60's race car look.

So now I gotta see if I can actually fit smaller rotors on a C5 suspension. I think 11.5" is the biggest that'll fit with 15's. This is gonna need some more research.

Looks like RCR uses 11.75" Willwood rotors/calipers to fit with 15" wheels. I'll have to check out these and see if they'll work with the C5 suspension pieces.
 
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