275/30R15
275 mm across the tread, a sidewall 30% of that — 83 mm — on a 15-inch rim. That puts the whole wheel at 21.5 inches tall.
- Sidewall
- 3.25"
- 83 mm
- Overall
- 21.5"
- 546.0 mm
- Circumference
- 67.5"
- 1.715 m
- Revs per mile
- 938
- per minute at 60 mph
What it needs to sit on
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Rim widths are the approved range for this section, published by ETRTO and
the Tire and Rim Association. Section width is quoted on one measuring rim;
the 5 mm per half-inch is the industry rule of thumb, not a guarantee.
It mounts on a rim between 7.5" and 10" wide, and the tread follows the rim: roughly 5 mm of section width for every half-inch, so about 263 mm across at the narrow end and 288 mm at the wide one. Written the way lift kits and wheel wells are, it is a 21.5×10.8R15 — tall by wide, in inches.
What fits instead
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Ride height is how much higher or lower the axle ends up — half the change in
overall height. Wheel wells and fender clearance move by the same amount.
Same 15-inch rim, height within 3%. Past that the speedometer starts lying and things begin to rub.
| Size | Height | Ride height | Speedo reads 60, you do | Compare |
|---|---|---|---|---|
| 265/30R15 | 21.3" -1.1 % | -3.0 mm | 59.3 mph | side by side |
| 255/30R15 | 21.0" -2.2 % | -6.0 mm | 58.7 mph | side by side |
| 255/35R15 | 22.0" +2.5 % | +6.8 mm | 61.5 mph | side by side |
If you fit something taller
A taller tire covers more ground per turn, so the needle reads low and the odometer counts short. Over ten thousand miles on the dial, the last column is what you really drove.
| Fitted instead | Reads 30 | Reads 50 | Reads 70 | Real miles per 10,000 shown |
|---|---|---|---|---|
| 265/30R15 | 29.7 mph | 49.5 mph | 69.2 mph | 9,890 |
| 255/30R15 | 29.3 mph | 48.9 mph | 68.5 mph | 9,780 |
| 255/35R15 | 30.7 mph | 51.2 mph | 71.7 mph | 10,247 |