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    Results 1 to 4 of 4
    1. #1
      Join Date
      Apr 2016
      Posts
      3

      Wheel and Tire size for stock suspension

      Hey Guys/gals,
      I know there are SEVERAL threads with wheel and tire size so I apologize. I have a 1976 Trans Am with stock suspension setup, and I am wanting to go with 17x10 or 18x10's on the rear. I do not want to have to roll my inner fender in order for them to fit, what size tire am I able to squeeze under there with the stock setup and what BS and offset is needed on the wheels? Thank you guys so much!

    2. #2
      Join Date
      Apr 2016
      Posts
      3
      Will a 285/40-18 fit with the stock setup? I've read so many forums I'm about to go cross eyed. Anyone have that setup? Looks like most are 275/40. I don't mind the 275/40 but wonder if I can go a touch wider?

    3. #3
      Join Date
      May 2015
      Location
      Island Lake, IL
      Posts
      815
      Country Flag: United States
      Weld wheels has a fitment guide if interested in checking that out.

      http://weldwheels.com/wp-content/upl...tion-Guide.pdf

    4. #4
      Join Date
      Feb 2003
      Location
      Houston, TX
      Posts
      3,445
      Country Flag: United States
      Every old car varies, as tolerances were not that precise back then. You also have to take into account if quarter panels or fenders might have been replaced along the lifespan. It is best to just measure your car for wheels, and it is very simple to do. I'll summarize for you. You only need a tape measure and a straight edge.

      1. Jack rear of car up and place rear axle on jackstands, so that the suspension is not hanging down. Remove wheels.
      2. Take the critical measurements at the 12 O' Clock position of the fender opening. Dimensions here: http://www.forgeline.com/wheel_fitment.php

      Calculating max tire width that can fit:



      3. Give yourself about 1/2" of clearance on the outside and back of the wheel. For example, if you measure 13" across (dimensions 1 + 2 on drawing above), then you can safely fit 12" of tire width. Check on tire manufacturer websites for the actual tire width of the tire you want to run. Look for "section width" or "overall width" on those websites.

      Calculating max wheel width that can fit:

      4. From those dimensions above, also keep the same 1/2" clearance outside, and backside of the wheel. Wheels are rated differently than tires. A wheel advertised at 10.0 inches actually measures at 11.0 inches across. So, you'll need 12.0 inches (dimensions 1+2) to fit that. Wheels essentially add 0.5" to the outside, and inside, of the wheel. 9.0 wheel measures 10.0 inches wide, 8.0 wheel measures 9.0 inches wide, etc... So, calculate the space you have, subtract an inch for clearance (0.5 outside and backside), and then subtract another inch for wheel width vs rated size. That gives you the max wheel width you can fit. You can use Dimensions 1 and 2 to figure out your backspacing requirements.

      Tony
      Co-Founder, LS1TECH.com


      Forged Wheel Dealer, Contact me for a quote!
      www.DV8Motoring.com






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