Here is some info for you.
Results of yesterday's wheel & tire test fitting w/ ROH wheels:
Factory wheels & tires:
17x8 w/ 245/45/17
55lbs each (wheel & tire)
5x120mm stud pattern
245/45/17 is still the best fit
255/40/17 fit but had to use a 8.5" wide wheel, the required backspacing hadthe wheels/tire sticking out too from the body line
275/40/17 didn't fit, using a 9" wide wheel, the tire was rubbibg the strut. Again using a different backspacing would have the set sticking out too far
ROH Drift R 17x8 w/ 245/45/17 - 47lbs
ROH Drift R 17x9 w/275/40/17 - 49lbs
275/40/17 fit no problems on a 17x9" wheel
These stick out just a little more than the factory tires, but I think they still look great!
Recommendation for 17" wheels: Use your factory tires and and put them on 17x8" custom wheels or 17x8" wheel front w/ 245/45/17 tires and 17x9" wheel rear w/ 275/40/17 tires
Personally I would just reuse the factory tires and put 17x8" wheels at all four corners. This will be cheaper to do and looks good.
By far the best way to go!!
18x8 w/ a 245/40/18 tire - fit is perfect
18x8.5 w/ 255/40/18 - again sticks out too far
18x9 w/ a 275/35/18 tire - fit is perfect
Recommendation for 18" wheels: Without a doubt the best set is 18x8 up front with 245/45/18 matched with 18x9 out back w/ 275/35/18. This set looks great, fits porportionally and lets you pick up some width out back. The ride quality is also great. Or use 18x8 and 245/40/18 at all four corners.
ROH Drift R 18x8 w/ a 245/40/18 tire - 49lbs
ROH Drift R 18x9 w/ a 275/35/18 tire - 51lbs
245/35/19 on a 19x8" wheel
275/30/19 on a 19x9" wheel
Recommendation for 19" wheels: GO BACK TO 18"!! While the look great on the car the ride quality is horrible. If you could care less about feeling every bump in the road and want all the look, these are for you. If you just gotta have them then use 19x8 w/ 245/35/19 front and 19x9 w/ 275/35/19 rear or the 19x9 w/ 245/35/19 all the way around.
I have some pics from the fitting I just need to get them off of my disc. I'll get some pics of my Goat with the set up I'm going with and personally recommend,
18x8 w/ 245/4018 front and 18x9 w/ 275/35/18 rear. If I'd been working at Pontiac this is what I would have sold the car with!!
By the way, anyone interested in ROH or other custom wheels contact me I now have pricing and availability info!!
18X8 on front with 245/40's 18X9 on the rear with 275/35 Michelin Pilot Sport AS's
Unfortunately Boyd put a +48 offset on the rears and they rubbed, so I rolled the fenders. Boyd was willing to make another pair but I was tired of waiting. It's been about three months already. I think a +55 would be a perfect offset for these on the rear and Boyd could definately do that.
NEW BOLT PATTERN FOR GENERAL MOTORS 5x120mm
WIDTH OFFSET WIDTH OF TIRE
7.0… +26/+65 215/225/235
7.5 +33/+61 215/225/235/245
8.0 +39/+55 225/235/245
8.5 +45/+48 235/245/255
9.0 (MAX) +48 245/255
8.0 +36/+65 245/255
8.5 +42/+65 245/255
9.0 +48/+65 255/265/275
9.5 +55/+64 265/275/285
Offsets greater than shown above will rub on rear fender lip (25mm fender lip).
Another fella posted this: "I have a set of wheels from ROH, the rears are 18x9 51mm 275/35 and front are 18x8 41mm 245/40, with Nittos, no need to roll. BFG or Dunlop you may need to roll?"
I have 18x8' rims with 245/40/18 Toyo meats in the front and 18x9' rims with 270/35/18's in the rear.