Wheel offset? Spacer size?
Thread Starter
Former Vendor
Joined: Mar 2003
Posts: 18,666
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From: Tampa FL
St. Jude Donor '07-'08-'09-'10-'11-'12'-'13-'14-'15
Wheel offset? Spacer size?
I just got a set of wheels with the following specs
FIT
1997-2008 CHEVROLET CORVETTE - C5 & C6
(2) - 19x9.5" FRONT WHEELS
(2) - 20x10.5" REAR WHEELS
FRONT 54MM OFFSET / 7.38 BACKSPACE
REAR 70MM OFFSET / 8.51 BACKSPACE
My car is a 99 C5 coupe with C6 Z51 brakes on it. I was told by a reliable source that the fronts will fit perfectly but I will need a spacer in the rear, most likely a 5/16th. I know I should know more about this but I am lazy and dont understand the whole wheel offset thing.
My question is what size spacer will I need? I dont think I can use an adapter since they start at 1" and that will be too much. What is the offset for the C5 ZO6 rear 18 x 10.5 wheel?
I only need a spacer wide enough to make up for that 6-8mm difference between C5 rear offset and the 70mm rear offset on these wheels right? Is there any difference between wheel spacers "made specifically for the corvette, camaro, S10 and those universal spacers?
Thanks for your time in advance.
Cajun
FIT
1997-2008 CHEVROLET CORVETTE - C5 & C6
(2) - 19x9.5" FRONT WHEELS
(2) - 20x10.5" REAR WHEELS
FRONT 54MM OFFSET / 7.38 BACKSPACE
REAR 70MM OFFSET / 8.51 BACKSPACE
My car is a 99 C5 coupe with C6 Z51 brakes on it. I was told by a reliable source that the fronts will fit perfectly but I will need a spacer in the rear, most likely a 5/16th. I know I should know more about this but I am lazy and dont understand the whole wheel offset thing.
My question is what size spacer will I need? I dont think I can use an adapter since they start at 1" and that will be too much. What is the offset for the C5 ZO6 rear 18 x 10.5 wheel?
I only need a spacer wide enough to make up for that 6-8mm difference between C5 rear offset and the 70mm rear offset on these wheels right? Is there any difference between wheel spacers "made specifically for the corvette, camaro, S10 and those universal spacers?
Thanks for your time in advance.
Cajun
Thread Starter
Former Vendor
Joined: Mar 2003
Posts: 18,666
Likes: 395
From: Tampa FL
St. Jude Donor '07-'08-'09-'10-'11-'12'-'13-'14-'15
Here's the info for stock wheels for the C5.
C5: STANDARD THIN SPOKE
Front 17x8.5 - 58mm
Rear 18x9.5 - 65mm
C5: Z06
Front 17x9.5 - 54mm
Rear 18x10.5 - 58mm
Can't tell you if you will have a clearance issue with your C6 Z51 brake setup or not. Hopefully someone out there with experience with that set up will chime in.
C5: STANDARD THIN SPOKE
Front 17x8.5 - 58mm
Rear 18x9.5 - 65mm
C5: Z06
Front 17x9.5 - 54mm
Rear 18x10.5 - 58mm
Can't tell you if you will have a clearance issue with your C6 Z51 brake setup or not. Hopefully someone out there with experience with that set up will chime in.
Thread Starter
Former Vendor
Joined: Mar 2003
Posts: 18,666
Likes: 395
From: Tampa FL
St. Jude Donor '07-'08-'09-'10-'11-'12'-'13-'14-'15
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Cajun,
Since your wheels are made to fit C6s, I'd guess no caliper clearance problem in your case, even w/o a spacer..
Offset sets the fitment of the wheel to the car...whether it sticks out of, or tucked into, the fenders.
Brake caliper clearance is more a function of the wheel design itself, spoke curvature, and outer lip thickness. Obviously pushing the wheel outward by using less offset, or spacers will also create more caliper clearance, but it's better to correctly offset the wheel first, then design it (the wheel) to provide the caliper clearance needed. This isn't always possible with pre-designed 1pc wheels, so people with big brakes often do use spacers to make the clearance necessary. But that's not your situation.
What I mean is...the C6 brakes have the same hub-to-caliper clearances as you do, because you have the C6 brakes. What is different between the two cars is the bodywork. The C6 isn't as wide of car, and the wheels were offset differently to compensate for that. Your new wheels will clear the calipers...you wish to push the wheels out slightly for aesthetic reasons (fit flush with the C5 fender), and to possibly avoid inner fender clearance issues caused by the increased backspace.
Hope that makes sense.
5/16" is about 8mm...I would not go any thicker than that w/o changing to longer studs. You don't have to make the wheels perfectly flush with the fenders...but a thin spacer will help to "split the difference" and make them fit better..
Since your wheels are made to fit C6s, I'd guess no caliper clearance problem in your case, even w/o a spacer..
Offset sets the fitment of the wheel to the car...whether it sticks out of, or tucked into, the fenders.
Brake caliper clearance is more a function of the wheel design itself, spoke curvature, and outer lip thickness. Obviously pushing the wheel outward by using less offset, or spacers will also create more caliper clearance, but it's better to correctly offset the wheel first, then design it (the wheel) to provide the caliper clearance needed. This isn't always possible with pre-designed 1pc wheels, so people with big brakes often do use spacers to make the clearance necessary. But that's not your situation.
What I mean is...the C6 brakes have the same hub-to-caliper clearances as you do, because you have the C6 brakes. What is different between the two cars is the bodywork. The C6 isn't as wide of car, and the wheels were offset differently to compensate for that. Your new wheels will clear the calipers...you wish to push the wheels out slightly for aesthetic reasons (fit flush with the C5 fender), and to possibly avoid inner fender clearance issues caused by the increased backspace.
Hope that makes sense.
5/16" is about 8mm...I would not go any thicker than that w/o changing to longer studs. You don't have to make the wheels perfectly flush with the fenders...but a thin spacer will help to "split the difference" and make them fit better..
Thread Starter
Former Vendor
Joined: Mar 2003
Posts: 18,666
Likes: 395
From: Tampa FL
St. Jude Donor '07-'08-'09-'10-'11-'12'-'13-'14-'15
Cajun,
Since your wheels are made to fit C6s, I'd guess no caliper clearance problem in your case, even w/o a spacer..
Offset sets the fitment of the wheel to the car...whether it sticks out of, or tucked into, the fenders.
Brake caliper clearance is more a function of the wheel design itself, spoke curvature, and outer lip thickness. Obviously pushing the wheel outward by using less offset, or spacers will also create more caliper clearance, but it's better to correctly offset the wheel first, then design it (the wheel) to provide the caliper clearance needed. This isn't always possible with pre-designed 1pc wheels, so people with big brakes often do use spacers to make the clearance necessary. But that's not your situation.
What I mean is...the C6 brakes have the same hub-to-caliper clearances as you do, because you have the C6 brakes. What is different between the two cars is the bodywork. The C6 isn't as wide of car, and the wheels were offset differently to compensate for that. Your new wheels will clear the calipers...you wish to push the wheels out slightly for aesthetic reasons (fit flush with the C5 fender), and to possibly avoid inner fender clearance issues caused by the increased backspace.
Hope that makes sense.
5/16" is about 8mm...I would not go any thicker than that w/o changing to longer studs. You don't have to make the wheels perfectly flush with the fenders...but a thin spacer will help to "split the difference" and make them fit better..
Since your wheels are made to fit C6s, I'd guess no caliper clearance problem in your case, even w/o a spacer..
Offset sets the fitment of the wheel to the car...whether it sticks out of, or tucked into, the fenders.
Brake caliper clearance is more a function of the wheel design itself, spoke curvature, and outer lip thickness. Obviously pushing the wheel outward by using less offset, or spacers will also create more caliper clearance, but it's better to correctly offset the wheel first, then design it (the wheel) to provide the caliper clearance needed. This isn't always possible with pre-designed 1pc wheels, so people with big brakes often do use spacers to make the clearance necessary. But that's not your situation.
What I mean is...the C6 brakes have the same hub-to-caliper clearances as you do, because you have the C6 brakes. What is different between the two cars is the bodywork. The C6 isn't as wide of car, and the wheels were offset differently to compensate for that. Your new wheels will clear the calipers...you wish to push the wheels out slightly for aesthetic reasons (fit flush with the C5 fender), and to possibly avoid inner fender clearance issues caused by the increased backspace.
Hope that makes sense.
5/16" is about 8mm...I would not go any thicker than that w/o changing to longer studs. You don't have to make the wheels perfectly flush with the fenders...but a thin spacer will help to "split the difference" and make them fit better..
Based on your advice I picked up a set of CCW billet 5/16" spacers earlier today for my rear wheels. Thanks again my brother!
