Modern Tire Sizes for Split-Window Buses with 14" and 15" Wheels


by Kabayo, cabayao@earthlink.net


I've posted this many times. This is the results of my tire size research:

European sized metric tires, such as a 185SR14 for example, do not have an 80% aspect ratio, but 82% or 83% (I forget which, but I think it's 82%). This changes things just a bit. I've added the Euro spec tires to the list of acceptable 14" and 15" sizes for buses.


Bentley says that the 3/4 ton (small nut) models came with a 6.40-15 tire, having a diameter of 27.16", +/- .24".

This makes the nearest European radial tire size a 185R15, and the nearest P-Metric size a 205/75-15.

Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
185/82-15      6.0in     13.5in  26.9in    84.6in         748        -0.6%
195/80-15      6.1in     13.6in  27.3in    85.7in         739        +0.7%
205/75-15      6.1in     13.6in  27.1in    85.2in         744         0.0%
225/70-15      6.2in     13.7in  27.4in    86.1in         736        +1.1%
255/60-15      6.0in     13.5in  27.0in    85.0in         746        -0.2%

How about running 14" wheels on a 3/4 ton (small nut) bus?

Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
205/75-15      6.1in     13.6in  27.1in    85.2in         744        0.0%
205/82-14      6.6in     13.6in  27.2in    85.6in         740       +0.5%
225/75-14      6.6in     13.6in  27.3in    85.7in         739       +0.7%
235/70-14      6.5in     13.5in  27.0in    84.7in         748       -0.6%
275/60-14      6.5in     13.5in  27.0in    84.8in         747       -0.4%

Good luck getting most of these on the back. I've gotten some big tires on the back of an old bus by letting the air out while wedging the tire between the drum and the body lip, and then refilling it after getting the wheel bolted up.


One ton (big nut) models came with 7.00-14 tires, having a diameter of 26.22", +/- .24".

This makes the nearest radial tire size a 195R14, and the nearest commonly available P-Metric a 205/75-14.

Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
185/82-14      6.0in     13.0in  25.9in    81.5in         777        -1.3%
195/80-14      6.1in     13.1in  26.3in    82.6in         767         0.0%
205/75-14      6.1in     13.1in  26.1in    82.0in         773        -0.7%
225/70-14      6.2in     13.2in  26.4in    82.9in         764        +0.4%
255/60-14      6.0in     13.0in  26.0in    81.8in         774        -0.9%

How about running 15" wheels on a one ton (big nut) bus?

Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
195/80-14      6.1in     13.1in  26.3in    82.6in         767         0.0%
175/82-15      5.6in     13.1in  26.3in    82.6in         767        +0.1%
185/75-15      5.5in     13.0in  25.9in    81.4in         778        -1.4%
195/75-15      5.8in     13.3in  26.5in    83.3in         761        +0.9%
205/70-15      5.6in     13.1in  26.3in    82.6in         767        +0.1%
235/60-15      5.6in     13.1in  26.1in    82.0in         773        -0.7%


If you're thinking of using a tire size not listed here, try the tire size calculator at http://www.miata.net/garage/tirecalc.html to see how it compares.


Last updated Tue Apr 10 22:12:41 CDT 2001
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