Wide rear rallyes

[SCOTI]

Originally Posted by OneBad71

Hello, I am starting over on a 71C10 build I started 10 years ago. Trying to figure out rear rim backspace because they need to be special ordered. I have the stock 12 bolt rear and I have added the wide Tubs. My plan is to go with 12inch wide US Wheel Rallye's in the back. They will do a custom backspace for me. I want to run the Hoosier Pro street 29x15x15 tires. I have been trying to figure it out but don't want to make a mistake on the rim backspace. So far i'm coming up with a 8.5in back space ? Has any one done this same tire and wheel combo on the wider rear axle like mine ? Based on my homemade Jig going off the drum face, I would have 8.5in in and 4.5in out. (13"overall rim width) Any help would be appreciated. Thank you

Originally Posted by OneBad71

Yours looks good. I am planning on the 29's but I was worrying about them being small ? My truck has the 3.5/5 lowering kit I put on 12 years ago. My plan is a 496 BB with TH400. . My rear end ratio is 3.42. Not sure how much 2inches changes much on gearing ? ( 29 verus 31" ) Wheels and tires are expensive , so i'm trying to do it one time lol. Thanks again!

29" x 3.42 @ 40mph= 1585rpm
@ 60mph= 2377
@ 70mph= 2774

31" x 3.42 @ 40mph= 1483rpm
@ 60mph= 2224
@ 70mph= 2595

Stock 'truck' ralley wheels are a common wheel to run. These 15x8's have 4" of back spacing. Widening to your specs would yield 8" of BS to keep things consistent as far as the spacing between the outer bedside lip & the edge of the wheel/tire.

Your proposed 8.5"BS would work. You might need to remove the bumpstop; might not.

FYI.... US Wheel might offer the wider/custom wheels but getting them can be an entirely different ordeal. I purchased 2qty 18x8" wheels & they were available/in stock via Summit. I placed a 2nd order for 2qty 18x9" wheels after verifying the fit of the 8" wheels. Five months later I still did not have my 2nd pair of wheels. I could not (nor could Summit) reach ANYONE @ US Wheel. Calls went to VM's after eventually going through & you never got a call back. The kicker? I had to 'eat' a penalty fee from Summit to return the 2qty 18x8" wheels because w/o the rear 9" wheels, the fronts were kind of useless.

Not my fault. Not Summits fault but they could have waived the fee since the wheels just sat around in a box for 6months. Be ready to possibly wait.....