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upgrading my t-birds tire size opinion

Discussion in 'The Hokey Ass Message Board' started by 57ford/60thunderbird, Apr 9, 2013.

  1. hey all i just ordered four 15 inch rims for my 60 t bird (originally 14 inch)

    and now i need good size tires for them i.e. your opinions

    first off my car is not a ground scraper i want a tire with decnt sidewalls no rubber bands

    im thinking 215 or 225's YES RADIALS 60's series on back and 70 or 75s on front

    rubber rake is ideal

    any ideas or suggestions? post pics if it will help

    my biggest problem is with the different series of tires and how the width effects the height
  2. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426


    When you break down a tire size, we will use 235/75r15 as an example, multiply the first number by .039 to convert it to inches. Then you can multiply that number by the second number with a decimal in front of it...235x.039=9.165 9.165x.75=6.874 You now know your tire section width would be a little over 9 inches wide and the side wall would be just shy of 7 inches high. If you multiply the second answer by 2 and add the rim size you will have the tire diameter so you will be able to see if you have any rake before you buy any tire.
  3. Gus68
    Joined: Jan 29, 2007
    Posts: 453

    from Minnesota

    I think you are a little backwards with a 60 seiries in back and a 70 or 75 on the front. Unless you want your "rubber rake" to put the front up higher than the rear.
  4. ok then what should i run ? i want a wider tire in the rear ive allways ran 60s on the back and 70s on the front

    Joined: Aug 9, 2011
    Posts: 136

    from Nanaimo BC

    How wide are the new rims?
    That might limit how wide of a tire you can safely run.
    Joined: Aug 9, 2011
    Posts: 136

    from Nanaimo BC

    Is that 7 inches from lip to lip?
  7. from bead seat to bead seat i would think
    Joined: Aug 9, 2011
    Posts: 136

    from Nanaimo BC

    You gotta know for sure. With a 6" wide rim (7 inches from lip to lip) you're safely limited to a 215 70 tire.
    If they are 7" wide (8 inches lip to lip) you can go to a 235 70 tire.
    You need to watch for tire rub on the front if you go taller and wider. Generally in the back going wider is the issue.
    Are these 15" rims stock?
  9. 53 effie
    Joined: Oct 21, 2004
    Posts: 241

    53 effie

    Yep, that's the way it was done in the 1970s that I remember. 70 series on the front and 60s on the back. I ran an E70-14 on the front and G60s on the back.. 6" and 8" slotted mags.

    For your Tbird though, I think I'd use maybe something like a 235/60r15 all the way around. I don't that I'd want to go even that low on a sidewall height. Maybe stick with 65 or 70 series would be better.
    Last edited: Apr 9, 2013
  10. the wheels are aftermarket steel with 4 inches of backspace
  11. Gotgas
    Joined: Jul 22, 2004
    Posts: 7,092

    from DFW USA

    Since all four wheels are the same dimensions, I would suggest keeping all four tires the same too. I would run a 215/75-15 for a more stock appearance or a 235/70-15 for a subtle 'fat tire' look.

    If you really want a rubber rake, keep the tires in that 215 to 235 width, and get tires in the height you like. Unfortunately radials top out at aspect ratio of 75 so your struggle will be finding two sizes of tire that fit your wheels width-wise, are noticeably different heights, and don't look too small. It's an art. :D

    The reason you remember 70s up front and 60s out back is because you were running radically WIDER wheels and tires in the rear - to the point where 60% of the rear tire height was more than 70% of the front tire height. Example, E70-14 in front and G60-14 out back, both are 26" tall, but the rears are 3" wider.

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