Offset for 13" wheel
Thread Starter
Racer
Joined: Oct 2003
Posts: 389
Likes: 1
From: Denver co
Offset for 13" wheel
Hi guys
I bought the carbon fiber rear fender that are 2" wider
I will install 13" wheel with 345 30 19 on the rear
I have more camber than stock for track setting
I calculated 40mm of offset does this seems correct
Also on the front I will have 295 30 19
I did not like the 19" but needed for the 380mm endurance caliper from APR
Thanks for your help
I bought the carbon fiber rear fender that are 2" wider
I will install 13" wheel with 345 30 19 on the rear
I have more camber than stock for track setting
I calculated 40mm of offset does this seems correct
Also on the front I will have 295 30 19
I did not like the 19" but needed for the 380mm endurance caliper from APR
Thanks for your help
Thread Starter
Racer
Joined: Oct 2003
Posts: 389
Likes: 1
From: Denver co
I can't find the specs for my CCW rear 13" wheels but I seem to recall 36mm being the offset.
If you do not already have one here is a wheel offset calculator link:
http://www.1010tires.com/Tools/Wheel-Offset-Calculator
And here is the OEM specs for the C5 and C6 wheels:
Backspace/offset dimensions are as follows:
C5 (coupe/vert):
Front 17x8.5", 58mm offset = 7.03" backspace
Rear 18x9.5" 65mm offset = 7.81" backspace
C5 Z06:
Front 17x9.5", 54mm offset = 7.38" backspace
Rear 18x10.5", 58mm offset = 8.03" backspace
C6 (coupe/vert):
Front 18x8.5", 56mm offset = 7.45" backspace
Rear 19x10", 79mm offset = 8.61" backspace
C6 Z06 and C6 GrandSport:
Front 18x9.5", 40mm offset = 7.22" backspace
Rear 19x12", 59mm offset = 8.82" backspace
C5 and C6 wheel circle:
5 on 4.75" (120.65MM)
Center hub dia. 70.3mm
I use the C5Z06 rear wheel specs for the current wheel in the calculator because those wheels are just inside the fenders on a C5.
Use your 40mm offset and 13" wide as the new wheel specs and run the calculator. The inner wheel clearance decreases by 14mm or about 0.55 inches. I do not believe that results in adequate clearance to prevent the wheels from rubbing the inner wheel wells.
Try the 36mm offset and you will see the inner clearance is now about 0.40 inches. My rear tires on the 13 inch CCW wheels will just rub the inner wheel wells on very hard corners....
My 13 inch CCW wheels are just a tiny bit (less than 1/8") inside the top of my rear flares when you hold a level to the top edge of the flares. My flares are L5's and they may be different than the brand you have
If you do not already have one here is a wheel offset calculator link:
http://www.1010tires.com/Tools/Wheel-Offset-Calculator
And here is the OEM specs for the C5 and C6 wheels:
Backspace/offset dimensions are as follows:
C5 (coupe/vert):
Front 17x8.5", 58mm offset = 7.03" backspace
Rear 18x9.5" 65mm offset = 7.81" backspace
C5 Z06:
Front 17x9.5", 54mm offset = 7.38" backspace
Rear 18x10.5", 58mm offset = 8.03" backspace
C6 (coupe/vert):
Front 18x8.5", 56mm offset = 7.45" backspace
Rear 19x10", 79mm offset = 8.61" backspace
C6 Z06 and C6 GrandSport:
Front 18x9.5", 40mm offset = 7.22" backspace
Rear 19x12", 59mm offset = 8.82" backspace
C5 and C6 wheel circle:
5 on 4.75" (120.65MM)
Center hub dia. 70.3mm
I use the C5Z06 rear wheel specs for the current wheel in the calculator because those wheels are just inside the fenders on a C5.
Use your 40mm offset and 13" wide as the new wheel specs and run the calculator. The inner wheel clearance decreases by 14mm or about 0.55 inches. I do not believe that results in adequate clearance to prevent the wheels from rubbing the inner wheel wells.
Try the 36mm offset and you will see the inner clearance is now about 0.40 inches. My rear tires on the 13 inch CCW wheels will just rub the inner wheel wells on very hard corners....
My 13 inch CCW wheels are just a tiny bit (less than 1/8") inside the top of my rear flares when you hold a level to the top edge of the flares. My flares are L5's and they may be different than the brand you have
I play with your number and my 40mm versus your 36mm just confirm that I should not rub on the inner fender
Also do you have some serious camber because it will bring the wheel to rub more on the inside fender but give you more room on the outside
Which in fact remind me that I measured it the car was on the lift and the arm moving up will move it closer
I may not have the gap I am thinking to get
Thread Starter
Racer
Joined: Oct 2003
Posts: 389
Likes: 1
From: Denver co
In fact the car is on a lift, but I had no wheel to check.
I borrow my son wheel and measured it but I will have to disconnect the spring to really see the wheel going all the way to the top
so far I am still heading with 19x13 with 36mm offset and 19x10 with also 36mm offset
the front is to clear the brakes but I will need flare fender on the front
I borrow my son wheel and measured it but I will have to disconnect the spring to really see the wheel going all the way to the top
so far I am still heading with 19x13 with 36mm offset and 19x10 with also 36mm offset
the front is to clear the brakes but I will need flare fender on the front
Thread Starter
Racer
Joined: Oct 2003
Posts: 389
Likes: 1
From: Denver co
I just check and for a 345 30 19 tire the wheel should be between 11,5 to 12,5 and not 13"
I check with my wheel guys and in fact he recommend 12" wide too
this is also why I did not understand when you were saying I may rub with the inner fender.
I don't know when I switch from 12 to 13 but that was a mistake from me
by the way here is a pictures with a wagon wheel and the wide fender
the level is aligned with the inner lip of the fender
I check with my wheel guys and in fact he recommend 12" wide too
this is also why I did not understand when you were saying I may rub with the inner fender.
I don't know when I switch from 12 to 13 but that was a mistake from me
by the way here is a pictures with a wagon wheel and the wide fender
the level is aligned with the inner lip of the fender
Last edited by corvettefrance; Oct 20, 2015 at 12:47 PM.
