I'm trying to find new wheels for my66coupebecause of the 4 to 5 lug conversion. I know the stock backspacingis 4.5inches butthe wheels I want are the cragar ss style 15x7, http://www.jegs.com/webapp/wcs/store...55662_-1_36662, part number260-61715, the americanracing bullits areoverpriced. Butthequestionis with the backspacing of the cragars, its 4.125. I figured thatits about 6-9mm of difference. I'm going to run 225/60/15 on them, got my info from http://www.mustangmonthly.com/techar.../classics.html. Also I'm doing a suspension conversion that will remove the upper control arm so it won't be in the way. I was wondering if anybody could help me out and let me know if the fender is going to get in the way or look weird sticking out or anything before I order them. I wish I could go out to my car a measure myself but I'm a couple thousand miles away and I'm trying to get everythingin placebefore I come back from the desert. Also would running a 15x8 part number 260-61815 with I don't know what size tire work with the 15x7 or look odd, thanks for the help.

 

Anybody, its about 6inches farther out than a stock 4.5inch backspace 15x7, would it still be safe in the clearance department?

 

hey remicks,
have you checked the FAQ

i got torq thrust d's, 15x7 with 225/60's. they rub! But the tt'ds have 3.75 back spacing
i think the cragars with 4.125 are ok and almost certain they are ok with 225/50/15's

i dont know how they compare price wise but the other option is mag500's 15x7 with 4.25 bs. They look great on a 65/66 too.

 

Thanks for the help, I guess the cragars will work. Also yeah I tried the FAQ, but I'm deployed to the desert right now and almost everything internet wise is blocked, I wish I could of got to dodgestang's site but that was blocked too. I feel kind of bad asking questions that can be answered by the FAQ but I can't get to any site for the most part.

 

I spent some time yesterday working out some numbers and other stuffofflinebut didn't get them posted. Anyway,

Either 225/50 or 225/60 will work just fine on 15 x 8's. They'll also work on 15 x 7's, although steering response won't be quite as "crisp" and the ride will be slightly softer.

I can't give you any hard clearance numbers, but I can tell you how to estimate it. A word of warning - it's hard enough to describe thisclearly without writing a book or drawing sketches and finding a way to make them available, so I suggest printing this out and working with paper and pencil. I've used the dimensions for the wheels you mentioned, verified them against online information, and used the mfrbackspacing data for the 8" wheel.

You need to work through some offset calcs to determine where the outer edge of a 15 x 8 would be relative to the 15 x 7. The 15 x 7 offset is (approximately) 4.125" - (7" + 2 * 0.25")/2 = 0.375", while the 15 x 8 (with 4.25" backspacing) is about 4.25 - (8 + 2 * 0.25") = 0". That puts the middle of the 8" wheel 0.375" further outboard. Then you add half of the difference in wheel width (0.5") for a total of 0.875" that the 8" outer wheel flange is further out. That's your fender clearance side. That 0.25" is approximately the width of a steelie flange lip (alloys are closer to 0.5"). If you end up with REALLY close clearances to the wheel on your intended choice, you'll want the actual measurement.

There's more. For every inch wider rim that a tire is mounted on, the section width (measured between the widest point on the sidewalls) increases by about 0.40". Half of that is on the outside, so the very widest part of the tire will be about 0.88" + 0.20" = 1.08" further out when mounted on 8's as compared to being mounted on 7's. Similar math for the inner sidewall puts that about 0.33" further inboard when mounted on 8's (for suspension and steering component clearance).

I don't have enough information to make any estimates regarding clearance up front for steering, other than to say that on 8's the front-most and rear-most points on the outer tire shoulders will follow a slightly larger radius arc when mounted on the 8's. I think that would be about the same as the difference in offset, or about 3/8" in this case. Keep in mind that you probably won't have the OE amount of clearance even with the 7's, so there's at least one more trip through the numbers in order to compare your "what-if's" against what's actually there now.

If you spend the time to take careful measurements, and consider "vertical" wheel motion (actually, it isn't perfectly straight up and down, but anyway) you'll have a really good handle on things when it comes time to reach for your wallet.

Wish I could find a 'salute' smiley - you've certainly earned it.


Norm

 

Thanks Norm, I'm going to call my friend back home who is storing my car for me and ask him to do some measurements for me. From what I can figure already is that the 15x7 should work fine all around with 225/60 or 50's, but the 8's could cause problems up front but more than likely be alright out back. I used a tire size calculator and found that the 225/60/15 would be almost be the exact same size as the factory original 185/75/14 so up and down shouldn't be an issue if width isn't.

 

I checked Dodgestang's chart, and there is a guy running the 225/60/15 tires on a 15X7 wheel without any rubbing issues.

 

Cool, thanks Soaring.