Max tire/wheel size for 69 Mach 1

[bw_kc]

Want to stay with Magnum 500 style 15" wheels.  What is the max wheel size/offset i can install?  Hoping to install drag radials or MT E/T Streets.

Car is 69 Mach1

[rcodecj]

If you are willing to massage the front of the inner wheel well you can fit quite a bit, if not then that is the first clearance obstacle you will encounter.
I have ran 8" with 5.5" backspacing on a 275/60/15 and 10" with 5.5 backspacing with a 275/50/15 on my 69 mach1. The 10" could have had more backspacing, if I recall correctly 6" on the 10" rim would have cleared. I also run a 9" rim with 5.5" bs with a 275/60/15 on my 67 but ended up rolling the outer fenderwells for a bit more safety, it was close as that car is really low. I have ran a 27/10.50/15 Mickey Thompson ET street on my 67 on the 10" 5.5 bs rims but only at the track. I run as close as 1/4" clearance to the leaf spring with no problems, some people would not be comfortable with that.
Maybe Jay will chime in, I think his magnum 500's were custom backspacing and he came up with something around 6"-6.25" on a 10".

[machoneman]

If you are willing to massage the front of the inner wheel well you can fit quite a bit, if not then that is the first clearance obstacle you will encounter.
I have ran 8" with 5.5" backspacing on a 275/60/15 and 10" with 5.5 backspacing with a 275/50/15 on my 69 mach1. The 10" could have had more backspacing, if I recall correctly 6" on the 10" rim would have cleared. I also run a 9" rim with 5.5" bs with a 275/60/15 on my 67 but ended up rolling the outer fenderwells for a bit more safety, it was close as that car is really low. I have ran a 27/10.50/15 Mickey Thompson ET street on my 67 on the 10" 5.5 bs rims but only at the track. I run as close as 1/4" clearance to the leaf spring with no problems, some people would not be comfortable with that.
Maybe Jay will chime in, I think his magnum 500's were custom backspacing and he came up with something around 6"-6.25" on a 10".

I agree with the above, have 8" rear rims with a similar size tire, but 16". The front inner corner of the w/wheel does need trimming as does sometimes the rebound bumper sheetmetal (12 o'clock high, above the axle centerline). Once past that the leaf spring clearance is the issue. I'd also run that 1/4" minimal clearance as mentioned but only on a drag car not seeing regular and tight turns. A streeter would need more to prevent sidewall rash.

   

[rcodecj]

Good catch machoneman on the rebound bumper trimming. I trimmed it on my 67 but refuse to touch it on my 69.

9" Prostar, 5.5bs, 275/60/15 BFG drag radial

[machoneman]

There is also a great link below (Ford Muscle but it links to the Classic Mustangs Forum) for '69-'70 Mustangs. I can't say these are the absolute maximums but the chart does cover a range of tires sizes and diameters.

http://www.fordmuscleforums.com/mustang-pages-1965-1973/501463-max-wheel-size-69-mustang.html

[rcodecj]

[rcodecj]

[machoneman]

Gee, I should have just posted Dodgestang's website in my previous post! 

http://www.dodgestang.com/mustang.htm

Nice pics too rcodecj.  Great car and a good looking stance as well. 

[rcodecj]

[jayb]

I was going to chime in here but I think you guys have got it covered.  My 15X10s with a custom 6.5" backspacing didn't work with the tires I chose; section width of the tires was too big, and I ended up barely rubbing on both the leaf spring and the inner wheel lip.  This was after fairly extensive trimming of the wheel lip, bump stop bracket, etc.

From a drag tire perspective, I ran 10.50s and 10.60s on 15X8 magnums with the 4.5" backspacing, and 27" tall 9" wide M/T slicks.  This was with Cal Tracs, their monoleaf springs, and Ranch adjustable rear shocks, and a 4500 converter.  The car hooked like nobody's business with that setup, and if I hadn't gone with the supercharged engine later I'd probably still be running that combination.  If you've got the front and rear suspension worked out, you can do pretty well on a 9" slick.

[machoneman]

Yes, section width is often the one aspect that can bite you and cause rubbing, or worse, where one might not expect it. Even though the tire maker's list section widths (one sometimes has to hunt for this dimension btw) for each tire, one can't assume that section widths are identical for the exact same tire size between two makers. A 275/60/15 Goodyear tire does differ from the same size TA, M/T tire, etc. 

 

[rcodecj]

I was going to chime in here but I think you guys have got it covered.  My 15X10s with a custom 6.5" backspacing didn't work with the tires I chose; section width of the tires was too big, and I ended up barely rubbing on both the leaf spring and the inner wheel lip.  This was after fairly extensive trimming of the wheel lip, bump stop bracket, etc.

From a drag tire perspective, I ran 10.50s and 10.60s on 15X8 magnums with the 4.5" backspacing, and 27" tall 9" wide M/T slicks.  This was with Cal Tracs, their monoleaf springs, and Ranch adjustable rear shocks, and a 4500 converter.  The car hooked like nobody's business with that setup, and if I hadn't gone with the supercharged engine later I'd probably still be running that combination.  If you've got the front and rear suspension worked out, you can do pretty well on a 9" slick.

Jay,
Can you post the part number of the M/T slick that you ran?
I haven't been able to find a 27" tall slick at 9" wide.
http://www.mickeythompsontires.com/strip.php?item=ETDrag

[jayb]

It's the 3054.  It's officially a 28" diameter tire, but if you look at the specs the actual diameter is 27.3".

[rcodecj]

It's the 3054.  It's officially a 28" diameter tire, but if you look at the specs the actual diameter is 27.3".

That's the same exact slick that Jason Moulton from Mickey Thompson recommended for my 67 mustang.

[afret]

Have M/T 275/60-15 ET Street Radials on 15x10 wheels with 6.125 BS.  The tires are 12" section width on these wheels.   Went to disc brakes which pushes the wheel out about 1/8" compared to the drums so could go to 6.25" BS now.

[rcodecj]

Looks great alfret. What brand wheels?
Custom backspacing?

[bw_kc]

 

[afret]

Looks great alfret. What brand wheels?
Custom backspacing?

Thanks. Bogarts.  You can get just about any backspacing.

Have a pair of cheap 10" wheels with 6.5" BS which will be used for 28x9 bias slicks in case the radials don't hook well at the track.  Probably will have to use thin wheel spacers but that's fine.

[bw_kc]

Follow-up to my tire/wheel sizing.  I made an adjustable template.  I've got this set for a 27" tall tire and 11 1/2" width.  It would appear that I can do at least 6" backspacing and fit within the existing rear wheel-well.  I'm trying to fit the most tire possible w/o mini-tubbing.

Pics posted above:
afret's car     has M/T 275/60-15 ET Street Radials on 15x10 wheels with 6.125 BS
rcodecj's car has MT ET Street 27/10.50/15 on 10" rim, 5.5bs

Do you think i can fit the 3755R tire?  This is 27.8 diameter/9.5"-10.5" rim/12" cross section.   I found a company that can make magnum 500s with custom backspacing.  I figured I'd emulate afret's wheel with 6.125 BS.
http://www.jegs.com/i/Mickey-Thompson/672/3755R/10002/-1?parentProductId=753925

[rcodecj]

I doubt it, the 3755R 12.0 sec width is listed as on a 9.5" rim.
It will be around 12.2 sec width on a ten inch rim.
Anyway it would not fit on my car from my measurements.
On my car it would be approximately .075 from hitting the leaf spring.
Your car may vary.

[afret]

I used to run M/T L60-15 tires which were a bit larger than the 275/60 drag radials.  I had them on 9" wide rims with 5.5" BS (which would be the equivalent of a 10" wheel with 6" BS).  The section width was 12 1/4" and the diameter was about 28 3/8" on the 9" rim.  The section width would be similar to the 3755R on a 10" rim.

It fit OK but when I went to rear discs that pushed the wheel out about 1/8" more than the drums, the tire would rub a bit on the passengers side which is a bit tighter.  You could probably get it to fit but you'll have to trim the wheel opening lip or roll them.  And you will have to shape the inner fender toward the front for tire clearance.

I think it's better not to push it to the max though.  The 275/60 should be adequate.  If you want a tire that hooks better, look at the 275/60 Hoosier.  It's more of a race tire and is a bit larger than the M/T.  Also M/T is supposed to revise the 275/60 soon and make it more like the Hoosier. I think the Goodyear 275/60 is also more of a race tire than the M/T. 

This is the car with the L60-15 on the 9" rim when it had drum brakes:

[rcodecj]

Just remember, no two cars are exactly the same and some cars are not the same from side to side.
Afret is right, better not to push it to the max.