Tire and wheel size with backspacing

[Jason7121]

Have a 71 c10 lowered 4/6 that I'm building. It's time to pick wheels and tires out. I like the torque thrust 2 in 18" front and rear. I have stock axle width and stock control arms up front. Does anyone know what back spacing I will need? Want to run a 10" wide or wider in rear and 8" wide up front. Thanks for any advice on fitment.

[cruisinthe34]

Here's my 71 with 17" front and 18" rear Coy C-5 4.5 B/S front 5" B/S rear. Tire sizes 235/55R17 front, 255/55R18 Rear



Front:




Rear:

[RodnRudy]

I'm looking at the same set up and I'm going to run 5"back space in front and 5 1/2" in the rear

[Jason7121]

Nice looking truck. If I wanted to go 10" wide in the rear should I do more back spacing to put wheel further inward?

[Mike C]

My '69 has Legend 5 spoke wheels. 235 55 17 in the front on 17x8 4.5" backspace. The rear is 275 55 17 on 17x9 with 5" bs. Both rims are zero offset with those numbers. I'm using a 5 lug axle from a '72.

That's as big a tire that will fit without modifying the inner bed structure on my stepside. Since you didn't specify I assume you have a fleetside. If you go 10" with 6" bs that should work.

[Jason7121]

Yes fleetside want to use 10" wide rear rim

[Mike C]

Tape measure is your friend here. Put a straight edge from the axle wms and meausre to first interference both inside and out. add those together and remove 1" or so from each side. Then you will know what backspace you need as well as how wide a rim you can run. Also, what diameter? It's easier to run a 10" wide 18 than it is a 10" 16 because of the sidewall bulge of the tire. The lower profile larger rim diameter

[Jason7121]

Makes sime I'll measure it out. Thanks for advice appreciate it.

[Jason7121]

So let's say I have 5" from wms to front and 7" from was to Inside of bed and want to run a 10" wide wheel. I would take 5-1=4 and 7-1=6 so I would need 6" back space correct?

[Mike C]

That's how I would do that math. But you didn't answer what diameter rim are you looking at. You will require less clearance with a larger diameter rim. Personally, I think 18's are probably the sweet spot for appearance as well as tire availability.

If I was doing mine again I would go 18 instead of 17 but with that said, I wouldn't even consider anything smaller. Or larger for that matter! LOL

[cruisinthe34]

My rear Rims are 18 x 9.5"

[Jason7121]

18×10 rear and 18×8 front is what I want to use

[Mike C]

Looks that would work fine. 6" bs in the rear on the 10's and 4.5" bs on the front should be GTG.

[Jason7121]

Thanks everyone I just ordered torque thrust wheels 20×8 4.5 bs and 20×10 5.75 bs