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Sidewall

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.

102 mm sidewall661 mm · 26.0"
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

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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

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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 goComplaints
blister2
blowout1

Where the wheel is named, 2 of 3 were on the front — the end that steers.

What fits instead

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Same 18-inch rim, height within 3%. Past that the speedometer starts lying and things begin to rub.


SizeHeightRide heightSpeedo reads 60, you doCompare
235/45R1826.3" +1.1 %+3.8 mm60.7 mphside by side
245/40R1825.7" -1.2 %-4.0 mm59.3 mphside by side
265/40R1826.3" +1.2 %+4.0 mm60.7 mphside by side
275/35R1825.6" -1.7 %-5.8 mm59.0 mphside by side
235/40R1825.4" -2.4 %-8.0 mm58.5 mphside by side
275/40R1826.7" +2.4 %+8.0 mm61.5 mphside by side
245/45R1826.7" +2.5 %+8.3 mm61.5 mphside by side
265/35R1825.3" -2.8 %-9.3 mm58.3 mphside 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.


255/45R17115 mm sidewall — 13% more
255/35R1989 mm sidewall — 13% less
225/40R1990 mm sidewall — 12% less
285/40R17114 mm sidewall — 12% more
225/50R17113 mm sidewall — 10% more
235/50R17118 mm sidewall — 15% more

Tires graded in this size

Longest-lasting tread first. The grade is set by the maker and checked by regulators.


TireTreadwearWet grip
Bridgestone TURANZA LS100560A
Toyo Crusade HP500A
Venezia Strada II500A
CONTINENTAL ContiSportContact 5420AA
Hankook veNtus S1 evo3 (OE)420A
HanKOOK Ventus evo (OE)380A
Michelin Pilot Sport 4320A
MICHELIN Pilot Sport 5320B
Yokohama ADVAN Sport280AA
Vogue ADVAN Neova180AA
Pirelli P ZERO ROSSO Directional160AA

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 insteadReads 30Reads 50Reads 70Real miles per 10,000 shown
235/45R1830.3 mph50.6 mph70.8 mph10,113
245/40R1829.6 mph49.4 mph69.2 mph9,879
265/40R1830.4 mph50.6 mph70.8 mph10,121
275/35R1829.5 mph49.1 mph68.8 mph9,826
235/40R1829.3 mph48.8 mph68.3 mph9,758