Tire size calculator
Pick your current size and the one you're considering. Both are drawn to scale, with the differences worked out.
225/65R17 → 235/65R17: +1.8% height. Inside the usual 3% rule.
| Measurement | 225/65R17 | 235/65R17 | Difference |
|---|---|---|---|
| Overall height | 28.5 in | 29.0 in | +0.51 in (+1.8%) |
| Section width | 8.9 in | 9.3 in | +0.39 in (+10 mm) |
| Sidewall height | 5.8 in | 6.0 in | +0.26 in |
| Circumference | 89.6 in | 91.2 in | +1.6 in |
| Revolutions per mile | 707 | 695 | −12 |
| Ride height | +0.26 in |
Speedometer
With 235/65R17 fitted, a speedometer set up for 225/65R17 shows the first number when you are really doing the second.
- 3030.5 mph
- 4545.8 mph
- 6061.1 mph
- 7576.3 mph
Reading the result
Height matters most: it sets the speedometer reading, the ride height and whether the tire clears the wheel well. Width changes the contact patch and needs a rim that suits it. A new size within 3% on the same rim is a common swap. To change rim size, look up the plus and minus sizes on any size page, or start from the tire size chart.
Calculator questions
How much bigger can my tires be?
Most shops keep a replacement within 3% of the original overall height. Past that the speedometer and odometer are noticeably off, ABS and shift points can be affected, and the tire is more likely to rub.
Why does my speedometer read slow with bigger tires?
A taller tire travels farther each turn, so at the same wheel speed you cover more ground than the speedometer expects. With a tire 3% taller you are doing about 61.8 mph when it shows 60.
Does a wider tire change the speedometer?
Only if it changes the overall height. Going 10 mm wider at the same aspect ratio also makes the sidewall slightly taller, which is why 235/65R17 stands taller than 225/65R17.