255/40R18
255 mm across the tread, a sidewall 40% of that — 102 mm — on a 18-inch rim. That puts the whole wheel at 26.0 inches tall.
- Sidewall
- 4.02"
- 102 mm
- Overall
- 26.0"
- 661.2 mm
- Circumference
- 81.8"
- 2.077 m
- Revs per mile
- 775
- per minute at 60 mph
What it needs to sit on
It mounts on a rim between 7" and 9.5" wide, and the tread follows the rim: roughly 5 mm of section width for every half-inch, so about 243 mm across at the narrow end and 268 mm at the wide one. Written the way lift kits and wheel wells are, it is a 26.0×10.0R18 — tall by wide, in inches.
What goes wrong on this size
3 drivers have filed a complaint. 0 of them ended in a crash, and nobody was hurt. Nobody died.
3 of them name what let go, and it is most often blister. Bridgestone is named more than any other brand.
| What let go | Complaints |
|---|---|
| blister | 2 |
| blowout | 1 |
Where the wheel is named, 2 of 3 were on the front — the end that steers.
What fits instead
Same 18-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 |
|---|---|---|---|---|
| 235/45R18 | 26.3" +1.1 % | +3.8 mm | 60.7 mph | side by side |
| 245/40R18 | 25.7" -1.2 % | -4.0 mm | 59.3 mph | side by side |
| 265/40R18 | 26.3" +1.2 % | +4.0 mm | 60.7 mph | side by side |
| 275/35R18 | 25.6" -1.7 % | -5.8 mm | 59.0 mph | side by side |
| 235/40R18 | 25.4" -2.4 % | -8.0 mm | 58.5 mph | side by side |
| 275/40R18 | 26.7" +2.4 % | +8.0 mm | 61.5 mph | side by side |
| 245/45R18 | 26.7" +2.5 % | +8.3 mm | 61.5 mph | side by side |
| 265/35R18 | 25.3" -2.8 % | -9.3 mm | 58.3 mph | side by side |
Same height, different rim
Bigger rim, same overall height. Sharper steering, harsher ride, and far less rubber between your wheel and the next pothole.
Tires graded in this size
Longest-lasting tread first. The grade is set by the maker and checked by regulators.
| Tire | Treadwear | Wet grip |
|---|---|---|
| Bridgestone TURANZA LS100 | 560 | A |
| Toyo Crusade HP | 500 | A |
| Venezia Strada II | 500 | A |
| CONTINENTAL ContiSportContact 5 | 420 | AA |
| Hankook veNtus S1 evo3 (OE) | 420 | A |
| HanKOOK Ventus evo (OE) | 380 | A |
| Michelin Pilot Sport 4 | 320 | A |
| MICHELIN Pilot Sport 5 | 320 | B |
| Yokohama ADVAN Sport | 280 | AA |
| Vogue ADVAN Neova | 180 | AA |
| Pirelli P ZERO ROSSO Directional | 160 | AA |
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 |
|---|---|---|---|---|
| 235/45R18 | 30.3 mph | 50.6 mph | 70.8 mph | 10,113 |
| 245/40R18 | 29.6 mph | 49.4 mph | 69.2 mph | 9,879 |
| 265/40R18 | 30.4 mph | 50.6 mph | 70.8 mph | 10,121 |
| 275/35R18 | 29.5 mph | 49.1 mph | 68.8 mph | 9,826 |
| 235/40R18 | 29.3 mph | 48.8 mph | 68.3 mph | 9,758 |