Narrowing down the wheel and tire choices

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Kar

Active member
Joined
Mar 1, 2013
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Location
USA, KY
My Car
1973 Mach 1 Q code
I have decided on the wheel and tire for My 73 Mach, I plan on getting American Racing Ansen Sprints (Slots) and using the ford center caps, I plan on running 245-60's in front, and 255-60's in the rear, I want just a slight larger tire in the rear and want the car to have a very slight rake.

The question is if I should go with 15x7's or 15x8's, i want the same size all around so the dish is the same for appearaces. I know the 8" wheel will look better and make the tire appear wider.

I want the fender lips to set just above or even with the top of the tire, and do not want it to rub during suspension movement. The 8's have 4.5 backspacing, and the 7" have 4" backspacing, I know the 7's will clear everywhere, not sure about the 8's

 
Those 2 sizes/back-spacings should have the same offset, so they should fit similarly, the sidewall to sidewall width should be .4" wider with the 8"

 
Most likely the 255's would require an 8" wheel. But you should check the manufacturer. I believe i saw somewhere that OEM back space was 4" not 4.25 so you may find that they rub on the inside on the upper control arm. Bad news is that once mounted, tires and wheels are no longer returnable. Choose wisely.

 
I've seen 255's on 7" rims but they have the "balloon" effect and I'm not sure how safe they are. I've attached a link that kind of breaks it down that might help you make your choice.

Jim

http://rimringz.com/pages.php?pageid=53

 
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I have 245/60/15 BFG TA all around on 15x& Magnum 500s

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As the tire sidewall gets taller you can run a wider width tire on the same rim. With the 60 series a 255 is fine on a 7" rim (honestly, a 275/60 fits fine), where a 245/50 is kind of boarderline too wide for a 7" rim.

 
IMG_5409.JPG

Hi Kar,

I would definately go the 15x8 rims if you can. I think they look better than the 14's.

I'm running 245/60/15 rubber up front and 295/50/15 rear. All tires are Mastercraft Avenger GT's on 15x8 Magnum 500 rims all round. All rims have a 4 and1/2 inch backspacing. Overall diameters of front and back wheels are very close with similar rolling radius.

Front setup fits and works like a dream with no issues, but rear setup gave me very minor rubbing probs on wheel arch lips. Overcame that by installing 5 leaf springs (standard eyes) which gives me a higher stance and a firmer ride. This combo gives me good handling and a nice ride around town and on the open highway. The tires are fantastic.

Greg:)

 
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I know a 245 0r a 255 will work fine on a 7" or 8" wide rim, if using a 15" wheel and 60 series tire. the question is clearance, the 8' wide wheels will without a dout make the tire look better (meatier), but I don't want any fender lip rubbing in the rear if the suspension allows the body to drop down over the tire, I want the body to set about even with the top of the tire. I don't want the inside lip of the front wheel to conflict with upper A arm as some have complained. Most 7" wide wheels have 4.25" Backspacing, and the 8" wide wheels have 4.5" backspacing. The American Racing Ansen Sprints that I want actualy use a 4" backspacing on their 7" wide wheel, which would help the A arm clearance and the clearance between the tire and the driverside inner frame rail during a hard left turn, and a 7" wheel with a 4" backspacing in the rear would move the outside edge of the tire in 1/2" to allow a little more clearance, but dang-gon-it, the 8" wide wheels look so good. Is it really this hard.

 
Kar,

It can all get confusing sometimes with wheels. However, if you chose to buy Ansen Sprints 15x8 all round with 4.5 backspaceing, and chose 245/60/15 tires all round as well, you won't have any rub issues with fit or clearence with the front suspension, and won't have fit or rub issues at the rear as well.

I had rear fender lip rub issues, because i chose to put the very wide 295/50/15 tires on the back. A smaller wide tire won't create problems. This can be confirmed or denied if needs be by other forum members. Hope that helps.

Greg:)

 
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