275/40R20

275 mm across the tread, a sidewall 40% of that — 110 mm — on a 20-inch rim. That puts the whole wheel at 28.7 inches tall.

What it needs to sit on

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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 28.7×10.8R20 — tall by wide, in inches.

What goes wrong on this size

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14 drivers have filed a complaint. 2 of them ended in a crash, and nobody was hurt. Nobody died.

13 of them name what let go, and it is most often blowout. Pirelli is named more than any other brand.

Where the wheel is named, 8 of 14 were on the rear, and 4 on the front. 2 gave out as a spare, which is the one nobody checks.

What fits instead

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Same 20-inch rim, height within 3%. Past that the speedometer starts lying and things begin to rub.

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.

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.