[Z06] GTO spare front skinnies and the C6 Z06
01-10-2011, 09:26 PM
#1
Le Mans Master
Thread Starter
GTO spare front skinnies and the C6 Z06
Hello fellow drag racers.
I recently picked up a set of GTO Spares with M&H Racemaster front runner tires (4.50 x 26 x 17 bias ply) for my C6 Z06. Several of my local C6 Z51 buddies have been using this combination as an inexpensive drag pack for the front, but it required the replacement of their large Z51 brake package with the smaller base brakes setup in order to bolt the wheels on without any additional adapters. Not wishing to due this, I started reading and looking into what it would take to install the GTO's on my factory Z06 front brakes.
With my 18x9.5 repo Spider wheels and Nitto Invo 275/35/18's weighing in at 52 lbs per axle, I'm looking at saving a considerable amout of weight and lessen the rolling resistance with the GTO/M&H tire combo.
Suprisingly, the combination of GTO Spare wheel with a M&H 4.50 x 26 x 17 bias ply tires weigh in at a very light 23 lbs per axle !!! The billet wheel adapters add another 5 lbs to this package, so the tire/wheel/adapter weigh in at 28 lbs, or a savings of 24 lbs per axle, 48 lbs total off the front end.
While I spoke with one owner who ran a 3.25" adapter he said it came in pretty close to making contact with the caliper (though it still worked). I had also heard that a 3.8" adapter was required to clear the caliper. I went ahead and went with the smaller adapter but added an additional .25" (quarter of an inch) to the adapter width to make sure I had plenty of space....total adapter size was 88mm or 3.46" .
The adapters were also built hub centric to the Corvette hub (70.3mm) and wheel centric to the GTO Spare wheel (69.5mm). Standard stud bolt pattern of 5 x 120.7 mm (4.75") was selected for the hub side...5 x 120 mm (4.72") was selected on the wheel side, with an OEM stud size of 12 x 1.5.
All in all, everything came out great with the wheel and adapter being hub centric and proper fitment in the wheel well and the manufacture delivered the goods exactly one week after I placed the order
In conclusion:
1) Billet wheel adapter at 88mm width (3.46")
2) Adapter hub centric at 70.3mm to the Corvette hub
3) Adapter wheel centric to GTO spare at 69.5mm
4) wheel studs are 12mm x 1.5
5) bolt pattern is Corvette at 5 x 120.7mm (4.75") on hub side, 5 x 120mm (4.72") for wheel side (GTO bolt pattern)
6) use open ended "bulge" acorn lugs nuts...12mm x 1.50 right hand thread for both adapter mounting and wheel lug nuts.
PM me for information on the vendor I used.....adapters were $220.00 plus shipping for the pair.
I recently picked up a set of GTO Spares with M&H Racemaster front runner tires (4.50 x 26 x 17 bias ply) for my C6 Z06. Several of my local C6 Z51 buddies have been using this combination as an inexpensive drag pack for the front, but it required the replacement of their large Z51 brake package with the smaller base brakes setup in order to bolt the wheels on without any additional adapters. Not wishing to due this, I started reading and looking into what it would take to install the GTO's on my factory Z06 front brakes.
With my 18x9.5 repo Spider wheels and Nitto Invo 275/35/18's weighing in at 52 lbs per axle, I'm looking at saving a considerable amout of weight and lessen the rolling resistance with the GTO/M&H tire combo.
Suprisingly, the combination of GTO Spare wheel with a M&H 4.50 x 26 x 17 bias ply tires weigh in at a very light 23 lbs per axle !!! The billet wheel adapters add another 5 lbs to this package, so the tire/wheel/adapter weigh in at 28 lbs, or a savings of 24 lbs per axle, 48 lbs total off the front end.
While I spoke with one owner who ran a 3.25" adapter he said it came in pretty close to making contact with the caliper (though it still worked). I had also heard that a 3.8" adapter was required to clear the caliper. I went ahead and went with the smaller adapter but added an additional .25" (quarter of an inch) to the adapter width to make sure I had plenty of space....total adapter size was 88mm or 3.46" .
The adapters were also built hub centric to the Corvette hub (70.3mm) and wheel centric to the GTO Spare wheel (69.5mm). Standard stud bolt pattern of 5 x 120.7 mm (4.75") was selected for the hub side...5 x 120 mm (4.72") was selected on the wheel side, with an OEM stud size of 12 x 1.5.
All in all, everything came out great with the wheel and adapter being hub centric and proper fitment in the wheel well and the manufacture delivered the goods exactly one week after I placed the order
In conclusion:
1) Billet wheel adapter at 88mm width (3.46")
2) Adapter hub centric at 70.3mm to the Corvette hub
3) Adapter wheel centric to GTO spare at 69.5mm
4) wheel studs are 12mm x 1.5
5) bolt pattern is Corvette at 5 x 120.7mm (4.75") on hub side, 5 x 120mm (4.72") for wheel side (GTO bolt pattern)
6) use open ended "bulge" acorn lugs nuts...12mm x 1.50 right hand thread for both adapter mounting and wheel lug nuts.
PM me for information on the vendor I used.....adapters were $220.00 plus shipping for the pair.
Last edited by FNBADAZ06; 01-13-2011 at 05:13 PM.
01-10-2011, 11:28 PM
#3
Race Director
This setup looks like it will put a great deal of force on the wheel bearings as the whole wheel/tire assembly appears to be outward of the rotor. A short trip to the track and back might be ok.
01-11-2011, 01:01 AM
#4
Race Director
Member Since: Sep 2007
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C6 of Year Finalist (performance mods) 2019
Just curious, but will the Z06 caliper brackets interchange with the base or Z51/F55 brackets so that the base rotors can be used? Of course, the caliper would need to be swapped too.
I'd guess somewhere around a 18-20 pound saving per wheel vs. the spacer.
I'd guess somewhere around a 18-20 pound saving per wheel vs. the spacer.
01-11-2011, 10:09 AM
#6
Le Mans Master
Thread Starter
01-11-2011, 12:26 PM
#7
Drifting
Looks good...thanks for the information!! Just be careful when running that Bias Ply front with anything other than a bias ply rear. It causes for a scary ride!
01-11-2011, 01:04 PM
#8
Le Mans Master
Thread Starter
No doubt !!! I'm currently running the bia ply MT ET Streets with my radial Nitto Invo's up front....makes for an interesting feeling at the top of the traps.
03-23-2013, 10:01 AM
#11
Le Mans Master
Has any one ever looked at flipping the GTO spare around for mounting in case of flat? I have Z06 wheels and front brakes on my ZR-1. Looking for a spare since I don't use RFs but I do have a spare tire carrier in rear.
Update: looking at pic it appears its not going to clear.
But maybe would need smaller spacer.
Update: looking at pic it appears its not going to clear.
But maybe would need smaller spacer.
Last edited by Dominic Sorresso; 03-23-2013 at 10:03 AM.
03-23-2013, 12:46 PM
#12
Racer
How much less spacer do you think you could run? I would want to be running the absolute minimum to decrease the offset from the centerline. Also, where would it make contact first as you decrease the offset?
Last edited by Sawbladz; 03-23-2013 at 12:49 PM.
07-21-2015, 09:46 PM
#14
1st Gear
Member Since: Jul 2015
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C6 Spare tire from a Pontiac GTO
I have a 2006 Corvette Z51 (with larger brakes). To make a 2004 - 2006 Pontiac GTO spare work on my car, I purchased an adaptor from Adaptec at www.motorsport-tech.com with the following specs:
Hub centric to Corvette hub (70.3mm)
Wheel centric to GTO spare (69.5mm)
Standard bolt pattern of 5 x 120.7mm (4.75") on hub side
Standard bolt pattern of 5 x 120mm (4.72") on wheel side
OEM stud size 12 x 1.5
Overall thickness of adaptor 67mm (2.64")
With lug nuts and shipping the adaptor came to $120 (make sure they know you only want one adaptor, since they are used to selling them in pairs for drag racing applications, etc.) The adaptor fit the vehicle and spare tire perfectly, although it is important to remove the assembly clips on the lug nuts to make sure the adaptor mounts flush to the rotor.
Installed on the front, the spare fit within 1/4" of the brake calipers, and the tire was appx. an inch outboard of the fender. It did not rub on the inner fender from steering lock to lock, and driven at speeds from 0 to 65 mph, did not trigger any error codes on the onboard computer. When the suspension was cycled, the tire did not hit the fender.
Installed on the rear, the adaptor was not strictly necessary as the spare tire will fit over the brakes with plenty of clearance, however the hub diameter on the spare would need to be enlarged slightly to fit the vehicle. I did not want to modify the rim, so again I installed it with the adaptor. With this in place, the spare tire was outboard of the fender by appx. an inch. Again, driven at speeds from 0 to 65 mph, it did not trigger any error codes, and when the suspension was cycled the tire did not hit the fender. In both tests, the tire performance was fine for a narrow spare tire, and there was no sense of instability or loss of traction in dry conditions.
I purchased the Pontiac GTO spare tire in excellent condition together with its jack, wrench/handle, wheel chocks, and tray holder for $175 shipped on e-bay. All of the items were used in my test and worked fine, including the 3/4" wrench integral to the handle. No other tools were needed, although I did use a hockey puck at the jacking point to avoid damaging the undercarriage or sill of the car.
I am well aware of the many discussions that have taken place on this forum about the safety/ wheel bearings/ error codes/ aesthetics/ etc. regarding this approach and am not looking to start these debates all over again. I simply wanted to share my results with those looking for an option in exigent circumstances.
Thank you to all those who posted before on this topic and many others. You do our enthusiast community a great service by sharing your experience and expertise.
Hub centric to Corvette hub (70.3mm)
Wheel centric to GTO spare (69.5mm)
Standard bolt pattern of 5 x 120.7mm (4.75") on hub side
Standard bolt pattern of 5 x 120mm (4.72") on wheel side
OEM stud size 12 x 1.5
Overall thickness of adaptor 67mm (2.64")
With lug nuts and shipping the adaptor came to $120 (make sure they know you only want one adaptor, since they are used to selling them in pairs for drag racing applications, etc.) The adaptor fit the vehicle and spare tire perfectly, although it is important to remove the assembly clips on the lug nuts to make sure the adaptor mounts flush to the rotor.
Installed on the front, the spare fit within 1/4" of the brake calipers, and the tire was appx. an inch outboard of the fender. It did not rub on the inner fender from steering lock to lock, and driven at speeds from 0 to 65 mph, did not trigger any error codes on the onboard computer. When the suspension was cycled, the tire did not hit the fender.
Installed on the rear, the adaptor was not strictly necessary as the spare tire will fit over the brakes with plenty of clearance, however the hub diameter on the spare would need to be enlarged slightly to fit the vehicle. I did not want to modify the rim, so again I installed it with the adaptor. With this in place, the spare tire was outboard of the fender by appx. an inch. Again, driven at speeds from 0 to 65 mph, it did not trigger any error codes, and when the suspension was cycled the tire did not hit the fender. In both tests, the tire performance was fine for a narrow spare tire, and there was no sense of instability or loss of traction in dry conditions.
I purchased the Pontiac GTO spare tire in excellent condition together with its jack, wrench/handle, wheel chocks, and tray holder for $175 shipped on e-bay. All of the items were used in my test and worked fine, including the 3/4" wrench integral to the handle. No other tools were needed, although I did use a hockey puck at the jacking point to avoid damaging the undercarriage or sill of the car.
I am well aware of the many discussions that have taken place on this forum about the safety/ wheel bearings/ error codes/ aesthetics/ etc. regarding this approach and am not looking to start these debates all over again. I simply wanted to share my results with those looking for an option in exigent circumstances.
Thank you to all those who posted before on this topic and many others. You do our enthusiast community a great service by sharing your experience and expertise.
