wide wheels & tires& backspacing?

[7434gmc]

wanting to mount 33x12.50x16.5's on the old factory g.m. 16.5x 9.75 rims..and or 285/75/16's on brand new "wheel vintiques" 16x10 factory style steel rims on the back of my 74 gmc 3/4 ton 2wd 8ft stepside( am converting to stake body)....the old factory16.5x 9.75 steel rims supposedly have 4.5 back spacing,...not sure on how to measure backspacing on vech ..if i can't find (3) stock 16.5x 9.75 factory rims that "should" go on without any issue's..& go with the new 16x 10's ..does anyone know what back spacing to order them with?...i have newer 90's 16x6.5's on the front with 245/75/16's for the front now,..if it makes any difference?

[special-K]

Standard backspacing works. Not trying to be wise but with regular wheels sizes like you're talking about the backspacing is always about the same and will work. I never knew the back spacing,never asked,and never cared on any of all the wheels I bought over the years. It's somewhere around 4" and you lay a straight edge across the rim and measure to the back of the mating surface.

[7434gmc]

NO.....i did'nt think u were trying to be wise, but what may be simple to u could be a $244 mistake (before shipping cost) for me, if i was wrong!..lol..they go "up to " 5" spacing on the rims, so "it is" possible to go "too much" on the back spacing!..but thank u for the response!..any & all help is appreciated!...have checked the b.spacing on the my new 16"s & should be ordering rims 1st of the month...thanks again for the help

[boosdad]

I think with even the 5" back space you will have plenty of room. One thing to think about with deciding on 16.5's or 16's is the cost and availability of the tires. I have an old class C Rv that I want the suspension from, but it has 16.5's, and boy are they expensive if I can find them local, and not as many size choices. something to factor into your decision.