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Hot Rods 7.50-17 Firestone’s max wheel width

Discussion in 'The Hokey Ass Message Board' started by threedudesracing, Dec 27, 2017.

  1. Anyone on here ever run a 7”wide wheel with 7.50-17 Firestone’s ??
     
  2. jeffd1988
    Joined: Apr 12, 2016
    Posts: 537

    jeffd1988

  3. gnichols
    Joined: Mar 6, 2008
    Posts: 10,907

    gnichols
    Member
    from Tampa, FL

    As a general rule, I like the rim width to equal the tire's specs for tread width. It seems to look good that way and it doesn't spread the tire's beads out too wide. That should get you close, anyway. Gary
     
    Elcohaulic likes this.
  4. I know the section width is about 8.25,hoping it would not look like side the walls are pulled away to bad from the bead of the rim. If anybody has any pictures it would help my decision making
     

  5. Did the tire section width look good in relation to the rim bead ? Thanks
     
  6. gnichols
    Joined: Mar 6, 2008
    Posts: 10,907

    gnichols
    Member
    from Tampa, FL

    I'm no expert by any means, but here's how I determine if a tire will look good on the rim and work like it should. Its also the formula I use to get the fronts and rears to look like matched sets even when the wheels and tires have different sizes - as in bigs n littles. Tire diameters, ride heights versus axle heights, gear ratios, etc. also closely related to your tire choice and you should also be looking at those specs when shopping for wheels and tires. Looks and performance go hand in hand.

    Other than getting the full specs on the tires (diameters, tread widths, section widths, speed ratings, plys, etc. and the factory recommendation for rim width) - like the specs you can get on the web or in a Coker catalog, the first thing you have to realize is that "6 inch" wheel is really about an inch wider between the outer edges of the rims - especially with mags. The advertised rim width is the size of that dip in the rim where the tire's bead seats and therefore narrower than the actual overall width of the wheel at the outer edge. That's important because what you choose for section width is related to the overall width of the wheel rim, not the rim size.

    What comes next is trying to determine what kind of "bulge" you want in the side wall. For example, if you had a tire with a 7" section width (the widest part of the tire between the sidewalls), and mounted it on a "6 inch" (7" actual) rim, that would mean that the sidewalls would be exactly the same width as the outer edge of the wheel. While the tire might fit the rim, there would be no "bulge" or cushion in the sidewalls. Good for auto-crossing, perhaps, but a stiff ride, me thinks.

    So what to do? In the example of the "6 inch" (7" actual) rim, I'd try to find a tire with about a 6-7" tread width and about a 8.5 - 9.0 inch section width. Splitting the difference between the section width and the actual rim width (9" less 7") leaves 2'" of difference, or "bulge," between the tire over the widest part of the rim. Divide that by 2, and you get 1" more in section width in the tire on each side of the rim's outer edge. That's a nice looking "bulge" or cushion in the side wall, IMHO. A tad more would be ok, but less perhaps not.

    Using the same approach, matching tread widths to "advertised" rim widths, and section widths to "actual" rim widths, you can match the look of most wheels and tires all around the car. I worked this out the first time on my 37 sedan street rod. The tires I chose for the front 14x6 rims and rear 15x7 rims had different tread widths and diameters but ended up with nearly identical sidewall "bulges" or cushion / section widths, and their tread widths looked good for the rim sizes. They looked pretty good on the car, almost like I planned it!

    One last example, if you had a narrower, more traditional 16 x 5 or perhaps 18 x 5 rim (6" actual) then I'd choose a tire with a 5 - 5.50 tread width and at least an 8" section width. Hopefully you can find a tire with the right rim size and overall diameter for your engine / trans / rear gear ratio to work well, too.

    Hope this helps, Gary
     
  7. Gary the particular tire as I indicated was the 7.50-17. It has a section width of 8.25 and a tread width of 6.32. The problem I have is I am running a full size Ford truck rear end with a three-link suspension and no way to narrow the rear end to accommodate a narrower set up. Plus I need to run at least a 17” wheel to avoid scrub line issues in the event of a flat tire. It gets worse LOL, after fitting the artillery wheels on the front with ww I’d really like to run them on the rear. The Firestone 7.50 whitewall appears to be biggest size in a 17 that’s available. A 7” wide wheel seems to be the narrowest wheel I can go to obtain a decent look
     
  8. gnichols
    Joined: Mar 6, 2008
    Posts: 10,907

    gnichols
    Member
    from Tampa, FL

    If you don't like the looks of a 6" wide wheel (too much gap between the inside of the tire and the body?), then you might consider a 6" rim with a 1/2" positive offset, which would put the inside of the tire / rim at the exact same distance from the body and the tire's sidewall as the 7" rim would have done with no offset. That's all I got, Gary
     
    Last edited: Dec 28, 2017
  9. I’m not sure how many offsets Coker has with their artillery wheels especially 17s plus a 5x5 1/2. Thanks for your help
     
  10. I checked on the 17” artillery and the only widths the 17” comes in are 7,8 and 9”. All the 7” have a 4 1/2” offset.
     

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