Got a chance on some older 8.5" Centerlines Auto drags with new 28-9 MT slicks, the guys say's they are 4.5" backspac, but I'm pretty sure they are really 4.875" backspace. I can get away with 4.250" max backspace. My question is, with the looooong lug bolts on my axles can I run a .625" wheel spacer? Is this safe? Is any wheel spacer safe for drag racing? I know that the rules say I must run open end lugs nuts with the lug sticking out a bit.
I am no expert, but I awesome that as long as the wheel is properly torqued it should not matter, the lug nuts do not know how wide the wheel is, the studs how ever do, so with longer studs and a fully threaded lug nut I think you should be okay, maybe someone with more experience can chim in though.
I have 8" Billet Specialties wheels with 4.5" back space, and I had to use a wheel spacer so my slick wouldn't rub on the spring. I just run a 9" slick also, and haven't rolled the fender lip yet. Can't remember if it's a 1/4 or 3/8". I know the spacing doesn't help you much...but I've been using the spacers on mine with a best 60' of 1.37, and haven't noticed anything abnormal on the studs. Possibly mini-tubbing and rolling the fender lip over the winter so I can fit a larger slick without back-halfing the car.
I use a .500 in spacer on mine. Have not had any issues. You have to have long studs though. There are rules about how much thread must be in the lug nut to be in compliance and be safe.
