225/75R15 measures 28.3″ overall diameter and 8.9″ section width. Sidewall height is 6.6″, circumference is 88.9″, and the tire turns 713 times per mile. Those figures are geometry off the stamped size, not a brand or load range.
225/75R15 dimensions
| Measurement | Inches | Metric |
|---|---|---|
| Overall diameter | 28.3″ | 718 mm |
| Section width | 8.9″ | 225 mm |
| Sidewall height | 6.6″ | 169 mm |
| Circumference | 88.9″ | 2257 mm |
| Revolutions per mile | 713 | 443 / km |
The stamped width is 225 mm (8.9″). The aspect ratio is 75, so the sidewall is 75% of that width, which is 6.6″. The rim is 15 inches. Overall diameter is the rim plus two sidewalls: 15 + 2 × 6.6″ = 28.3″.
Sizes near 225/75R15
A swap that stays inside about 3% diameter usually keeps the speedometer honest and clears the same well. 235/75R15 is a close neighbour at +2.1% diameter. The percent column opens both stamps in the comparison calculator.
| Size | Diameter | Width | vs 225/75R15 |
|---|---|---|---|
| 235/75R15 | 28.9″ | 9.3″ | +2.1% |
| 235/65R17 | 29.0″ | 9.3″ | +2.6% |
| 255/65R17 | 30.1″ | 10.0″ | +6.2% |
| 265/50R20 | 30.4″ | 10.4″ | +7.6% |
| 245/75R16 | 30.5″ | 9.6″ | +7.7% |
| 245/70R17 | 30.5″ | 9.6″ | +7.8% |
How to read the stamped size
225/75R15 is a metric size: width in millimetres, aspect ratio as a percent of that width, then the rim diameter in inches after the R. The how to read tire size page walks the whole sidewall, including load index and speed rating, which this page does not use.
Diameter and width tell you whether a size is in the same family as what you have. They do not tell you whether 225/75R15 clears your fenders, matches your wheel width, or is load-rated for the vehicle. Check the door-jamb sticker and the wheel well before you buy.
Speedometer and revs
At 713 revolutions per mile, a trip computer calibrated for 225/75R15 is reading true only while this diameter is on the truck. A taller replacement under-reads speed and distance by the same percent the diameter grew. A shorter one over-reads. The comparison calculator puts a second size next to 225/75R15 and shows the error at 60 mph.