Compare two sizes › Tire sizes
Tire size pages, by ladder
19 sizes have a page of their own: what the code means, every dimension, a drawing to scale, and every size within ±3 % of its diameter with the speedometer error it causes. We found no public list of the most-sold tire sizes that we are allowed to reuse, so which sizes get a page is decided by the rules printed with each group below, not by sales figures. For any other size, the calculator works it out.
Passenger-car ladder: 225/45R17 5
For each rim from 15 to 19 inches, pick the size with the closest overall diameter to 225/45R17 among widths 185 + 10 × (rim − 15) to 215 + 10 × (rim − 15) mm in 10 mm steps and aspect ratios 35–65 in steps of 5. Each step up in rim trades sidewall for width while the overall diameter stays within a few millimetres, so the speedometer barely moves.
| Size | Overall diameter | vs 225/45R17 | Sidewall | Revs per mile |
|---|---|---|---|---|
| 195/65R15 | 634.5 mm24.98 in | +0.0 %+0.2 mm | 126.8 mm | 807.4 |
| 205/55R16 | 631.9 mm24.88 in | −0.4 %−2.4 mm | 112.8 mm | 810.7 |
| 225/45R17 | 634.3 mm24.97 in | 0.0 %0.0 mm | 101.3 mm | 807.6 |
| 225/40R18 | 637.2 mm25.09 in | +0.5 %+2.9 mm | 90.0 mm | 803.9 |
| 225/35R19 | 640.1 mm25.20 in | +0.9 %+5.8 mm | 78.8 mm | 800.3 |
Passenger-car ladder: 215/55R17 5
For each rim from 15 to 19 inches, pick the size with the closest overall diameter to 215/55R17 among widths 185 + 10 × (rim − 15) to 215 + 10 × (rim − 15) mm in 10 mm steps and aspect ratios 35–65 in steps of 5. Each step up in rim trades sidewall for width while the overall diameter stays within a few millimetres, so the speedometer barely moves.
| Size | Overall diameter | vs 215/55R17 | Sidewall | Revs per mile |
|---|---|---|---|---|
| 215/65R15 | 660.5 mm26.00 in | −1.2 %−7.8 mm | 139.8 mm | 775.6 |
| 215/60R16 | 664.4 mm26.16 in | −0.6 %−3.9 mm | 129.0 mm | 771.0 |
| 215/55R17 | 668.3 mm26.31 in | 0.0 %0.0 mm | 118.3 mm | 766.5 |
| 235/45R18 | 668.7 mm26.33 in | +0.1 %+0.4 mm | 105.8 mm | 766.1 |
| 235/40R19 | 670.6 mm26.40 in | +0.3 %+2.3 mm | 94.0 mm | 763.9 |
Pickup and SUV ladder: 265/70R17 5
For each rim from 16 to 20 inches, pick the size with the closest overall diameter to 265/70R17 among widths 245 + 10 × (rim − 17) to 285 + 10 × (rim − 17) mm in 10 mm steps and aspect ratios 45–80 in steps of 5. Each step up in rim trades sidewall for width while the overall diameter stays within a few millimetres, so the speedometer barely moves.
| Size | Overall diameter | vs 265/70R17 | Sidewall | Revs per mile |
|---|---|---|---|---|
| 265/75R16 | 803.9 mm31.65 in | +0.1 %+1.1 mm | 198.8 mm | 637.2 |
| 265/70R17 | 802.8 mm31.61 in | 0.0 %0.0 mm | 185.5 mm | 638.1 |
| 265/65R18 | 801.7 mm31.56 in | −0.1 %−1.1 mm | 172.3 mm | 639.0 |
| 265/60R19 | 800.6 mm31.52 in | −0.3 %−2.2 mm | 159.0 mm | 639.9 |
| 295/50R20 | 803.0 mm31.61 in | +0.0 %+0.2 mm | 147.5 mm | 637.9 |
Flotation sizes 4
Inch-coded light-truck sizes: overall height × section width, then the rim. The rule: overall heights of 31, 33 and 35 in, one section width per height (10.50 in for 31, 12.50 in for 33, 12.50 in for 35), on 15- and 17-inch rims, keeping each combination whose sidewall, (height − rim) ÷ 2, is 8 to 9 in. That drops 31x10.50R17 (7 in sidewall) and 35x12.50R15 (10 in sidewall). Each page lists every metric size within ±3 % of its diameter; the closest one on the same rim is below, with your true speed on it when a speedometer set up for the flotation size shows 60 mph (and 100 km/h).
| Size | Overall diameter | Closest metric, same rim | Really doing | Revs per mile |
|---|---|---|---|---|
| 31x10.50R15 | 787.4 mm8.0 in sidewall | 255/80R15+0.2 % | 60.1 mph100.2 km/h | 650.6 |
| 33x12.50R15 | 838.2 mm9.0 in sidewall | 305/75R15+0.0 % | 60.0 mph100.0 km/h | 611.2 |
| 33x12.50R17 | 838.2 mm8.0 in sidewall | 315/65R17+0.4 % | 60.2 mph100.4 km/h | 611.2 |
| 35x12.50R17 | 889.0 mm9.0 in sidewall | 305/75R17+0.0 % | 60.0 mph100.0 km/h | 576.2 |
How to read a ladder
A plus-sizing ladder keeps the overall diameter and moves everything else: one inch more rim, about 10 mm more width, a lower sidewall. On the 265/70R17 ladder the 16-inch step is 265/75R16 and the 20-inch step is 295/50R20; both stay within about 1 mm of the anchor's diameter, so the speedometer and gearing are unchanged, but the 20-inch tire has about 38 mm less sidewall to absorb a pothole or air down on a trail. The diameter is the only thing the ladder holds constant.
What these pages cannot tell you
- Whether a size is right for your vehicle. Clearance, wheel width and offset, load rating and what the maker approves are not in the size code. Start from the sizes on the door-jamb placard, then check the physical clearance.
- Exact real-world size. These are nominal figures for a new, unloaded tire; makers build to a tolerance of a few percent (on a 35 in tire, 2 % is 0.7 in), and a new tire with 8 mm of tread is about 13 mm taller than one worn to 1.6 mm.