Mustang and Fords Wheel & Tire Chart

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BIGREDRASA

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Ford Mustang Wheel Fitment - One Size Does Not Fit All

'65-'66 MUSTANGS
Wheel Backspace Tire Size
15x6 4.000 P215/70R15
15x7 4.250 P225/60R15
15x8 4.500 P235/60R15
16x7 4.250 P225/60R16
16x8 4.500 P225/50R16
17x7 4.250 P205/50R17
17x8 4.500 P235/45R17

'67-'70 MUSTANGS
Wheel Backspace Tire Size
15x6 4.000 P215/70R15
15x7 4.250 P225/60R15
15x8 4.500 P225/60R15
15x9 5.500 P235/60R15('69-'70 only)
16x7 4.250 P205/55R16
16x8 4.500 P255/50R16
17x7 4.250 P205/50R17
17x8 4.500 P235/45R17
17x9 5.500 P245/40R17 (P275/40R17rear axle)
18x10 6.500 P225/40R18
20x10 5.000/custom P225/35R20 (rear axle only)

Decoding Tire Codes
The series of letters and numbers on a tire's sidewall tell a lot about what you're getting for your money as well as the tire's capabilities. The first series of numbers denotes tire size. After that, the two most important things to look for are the service description and the uniform tire-quality grade or UTQG.

Using the information in the service description, we know that a set of our P215/60R16-94T tires will carry a load of 5,908 pounds at up to 118 mph safely. While the load range is fine for our '67 Mustang, the 118 top speed could easily be exceeded, calling for a tire with a higher speed rating. We should note that the speed rating doesn't apply to tires that are worn out, repaired, damaged, retreaded, or not properly inflated.

LOAD INDEX CAPACITY (IN LBS)
71 761
72 783
73 805
74 827
75 853
76 882
77 908
78 937
79 963
80 992
81 1,019
82 1,047
83 1,074
84 1,102
85 1,135
86 1,168
87 1,201
88 1,235
89 1,279
90 1,323
91 1,356
92 1,389
93 1,433
94 1,477
95 1,521
96 1,565
97 1,609
98 1,653
99 1,709
100 1,764
101 1,819
102 1,874
103 1,923
104 1,984
105 2,039
106 2,094
107 2,149
108 2,205
109 2,271
110 2,337

SPEED RATING MAX MPH
M 81
N 87
P 93
Q 99
R 106
S 112
T 118
U 124
H 130
V (VR) 149
W (ZR) 168
Y(ZR) 186
 

frogmn666

Well-known member
What about 14" wheels and tires? I just bought some used 14x7" Western wheels that have 185-75/14s on them. How big can I go without rubbing on my `66 Mustang coupe 200 auto? Don't want to go too big and kill my gears.
 

66200i6

Famous Member
The wheel and tire size you quoted are just a little under sized at 25.16â€￾ diameter.

The original Bias Ply’s were the 195/78 x 14’s which works out to about 25.98â€￾ diameter. Consider that the Bias Ply’s are stiffer and produced a narrow foot print on the road. The stance of the car would be a smug taller than a Radial of the same size if they existed. The closest size used today is the 195/75R x 14’s which works out to 25.52â€￾ diameter. With the Radials stance and wider shorter foot print, the diameter is actually a tad smaller than the 25.52â€￾ with the tire on the road.

You can play with different sizes to get the diameter up but I don’t know that it is worth the effort just yet. Just use your new tires and wheels and keep the air pressure up. The higher pressure will keep the diameter and the gas mileage up.

Have fun, Ric.
 

frogmn666

Well-known member
I got this car when my dad died in 03. It currently has worn out P215/70R14s on the rear and P205/75R14s on the front. I haven't driven it much, but I do remember something rubbing in the front when I went up a curb. The 185s on my new(used)wheels are worn out too.
 

Ba Mustang

Well-known member
I run 16x7 205/60R16 and 235/60ZR16 on my 67. I have a backspacing of 4.87", but I run 1" thick wheel adapters all around to make them fit. I am using the early 90s pony rim.
 

SoCar72

Well-known member
I found what seems to be a popular misconception or underestimation for tire/wheel sizing for the '69/'70 Mustangs. The maximums seem a little conservative.

I'm running:

Front - 17x8's, 4.75" backspacing and 245/45's with a stock suspension. The only clearance issue was at max turn, I ground the protruding lip on the stock 4-bolt upper arm about 1/8" to clear the balance weights. Sticky-strip weights would have cleared. I later lowered the front by 2.5" (1" upper arm drop and 1" shorter 620lb coils. I rolled the inner fender lip (2" dia pipe over the tire) to clear max turn/compression issues, such as a hard dipping turn.

Rear - 17x9.5", 5.875" backspacing and 275/40's with the stock 9" rear. I have plenty of clearance to run in an additional .75" and out about another .75". I later dropped the rear by 2", still no clearance issues. Measurements indicate clearance for a pair of 295/45 MT ET Radials.

For what it's worth, on my '63 Falcon (all stock suspension, sway bars added), I'm running 16x7's, 4.5" backspacing with 215/60's on all 4 corners. All cleared sitting still and driving smooth, found some spirited driving clearance issues. So, I rolled the front fender lips and trimmed back the rear lips about 1/4". All seems clear. Clearance indicates I could have gone about another .375" in on the front and .75" in the rear.
 

SoCar72

Well-known member
Tire size decoding: This is a general rule of thumb to the geometry of tire sizing, but varies a little by manufacture based on where in the construction their specs are measured.

255/50 R17 (I chose easy numbers for this example)
255 = width in mm. Multiply by .0394 (mm to inch conversion) = 10.047" overall section width.
10.047 x .5 (50 - this is the aspect ration as a percent / 100 to convert to decimal, or move the decimal 2 spots left) = 5.0235" side wall height.
5.0235 x 2 (lower side wall plus upper side wall) = 10.047" of side walls (this is redundant with 50 series tires but important for all others).
10.047 + 17 (wheel diameter) = 27.047" of overall height.

255/50 R17 is about 27" tall x 10" wide. I favor sizing a tire 1" - 1.5" wider than the wheel since the wheel lips extend about .5" beyond the bead where the width is measured, this is design and material dependent, but a rough typical. Lower aspect tires call for a closer tire/wheel width variance, and larger aspect allows greater variance. I try to never let the tire get less than 1" wider than the wheel as the danger of striking the wheel lip on curbs and such increases (parallel parking, anyone?). Not to mention a wheel that's wider than the tire just looks silly and under thought.

True section width will vary with wheel width as the beads will push/pull the sidewalls from it's natural position and the curvature of the sidewall will vary by design.

Tread width will vary by aspect ratio - lower aspect increases tread width, higher decreases, when comparing the same brand/style tire across different aspects.

Finally, all varies by manufacturer, hence the "rule of thumb of geometry" clause. However, the manufacturer's true specs, as I have found, usually vary less than about 1% from the calculations. The tread width is the largest variable as it determined by tread design with variances as great as 10% across the same size tire range.

However, typically, I have noticed that Asian tire companies tend to under size the tires, domestic tends to over size, and European are down the center. Suggesting to me that the Asian companies tend to dimension to the outside of the construction, domestic to the inside, and European to the centerline of construction. All contribute to the 1% variable. Like the English language, there are exceptions to the exceptions.

Ultimately, the math and the true specs never match exactly, but they run close enough together to serve as a tire size selection guide.

I usually turn the formula around backwards, starting with a target overall dimensions (say 27" x 10") for the application and then determine what size tire and wheel can get me the final specs I am looking for. Then search the true specs for the candidate tires that yields me the most desired result considering tread width and rotational distance or roll-out (the distance the tire covers per revolution) which does not necessarily equal the circumference of the tire due to rubber stretch and compression. These minute fluctuations can equal surprisingly different results.

Two same height tires with two different roll-out specs (usually measured as number of full revolutions at 45mph) will give you an idea of how much the tire squats under load. The higher number tire indicates that the tire stands more proud, hence more fuel efficient due to greater distance covered per revolution and less rotational resistance. The lower number tire indicates greater traction due to a longer contact patch. Traction is the sole result of how much tire rubber (tread design is also a consideration) makes contact with the road as defined by the tread width x the contact patch length. This is excluding the rubber compound, indicated by the wear rating (high number = hard, low number = soft) or specialty interest such as drag radials, road race, etc. This info may seem ultra-minute, but can mean the difference of a few tanks of gas over an oil-change, or more tire spin from the traffic light launch.

As with everything else, all is based on variables. Wear rating isn't just based on the rubber hardness, but also tread and sidewall plies and material (steel vs. rayon vs. polyester vs. nylon, etc.). The variables are almost infinite, and unless you're in competition the minutia is predominantly negligible, but fun to think about. [-says the gearhead nerd]

My apologies for the dissertation. This was supposed to be a brief formula synopsis.
 

Bayrunner

Well-known member
O.K. Help me understand please. On a 66 Stang with 4 lugs. My options are limited on wheels. Can I fit a 17x8 wheel on this car without rub?
 

SoCar72

Well-known member
Quite possibly. I'm running 17x8's with 4.75" back space on my '69 with no clearance issues. I would suspect that you should be able run a similar bs on your 66. I have read that 8's are common with minor or no clearance mods. Worst should be that you roll the inner lips a little.

I would err towards a little too deep in the bs department and space the wheel out. You can always space the wheel out, pulling it further in is very difficult.
 

Vin Man

Famous Member
I am in the process of converting my 67 Mustang to a 5 lug setup and have started looking for wheels. I have found these locally:

http://phoenix.craigslist.org/evl/pts/1426078333.html and I'm wondering if they will fit on the Mustang. They are from a 2006 Mustang. From the look of them, the backspacing looks different than the wheels used in 67. I'm wondering if the fronts will rub when I turn. Any thoughts?
 

kukm66

Famous Member
Stock tires on a 14" rim with 4.5" backspacing will rub on the tips of the A-frames.
This is the main area where rubbing occurs.
Going to a 60 or 65 series will solve the problem with the fender lips up front depending on the size.
Most people go with a 215 x 60 or 215 x 65.
 
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