tireheight.com

245/40R18 in inches

A 245/40R18 tire is 25.7″ tall and 9.6″ wide, and fits a 18″ wheel. In inches it is written 25.7×9.6R18.

Diameter25.72″
Width9.65″
Sidewall3.86″
245/40R18 drawn to scale: 25.72 inch diameter, 3.86 inch sidewall, 18 inch wheel, 9.65 inch tread width18″ wheel3.86″25.72″ overall9.65″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 245/40R18 tires really are

Heights published by BFGoodrich, General, Michelin and Toyo for all 31 tires in this size. Their published revolutions per mile work out to 24.9–25.2″ under load (below).

Real 245/40R18 tires measure 25.70–25.95″, against 25.72″ from the size code. They run both taller and shorter than the size code.

  1. Toyo Proxes R1R25.95″ +0.24″
  2. Michelin Pilot Sport All-Season 4 · 225.70–25.90″ +0.18″
  3. BFGoodrich Advantage Control · 225.71″ −0.01″
  4. BFGoodrich g-Force COMP-2 A/S PLUS25.71″ −0.01″
  5. BFGoodrich g-Force Phenom T/A25.71″ −0.01″
  6. BFGoodrich g-Force Rival S25.71″ −0.01″
  7. BFGoodrich g-Force Rival+25.71″ −0.01″
  8. Michelin Pilot Alpin 525.71″ −0.01″
  9. Michelin X-Ice Snow25.71″ −0.01″
  10. Toyo Celsius II25.71″ −0.01″
  11. Toyo Extensa HP II25.71″ −0.01″
  12. Toyo Observe G3-Ice25.71″ −0.01″
  13. Toyo Proxes R888R25.71″ −0.01″
  14. Toyo Proxes Sport A/S25.71″ −0.01″
  15. General AltiMAX Arctic X25.70″ −0.02″
  16. General AltiMAX RT4525.70″ −0.02″
  17. General AltiMAX365 AW25.70″ −0.02″
  18. General G-MAX AS0725.70″ −0.02″
  19. General G-MAX RS25.70″ −0.02″
  20. Michelin CrossClimate225.70″ −0.02″
  21. Michelin Pilot Sport 325.70″ −0.02″
  22. Michelin Pilot Sport 4 · 225.70″ −0.02″
  23. Michelin Pilot Sport 4 S25.70″ −0.02″
  24. Michelin Pilot Sport Cup 2 Connect25.70″ −0.02″
  25. Michelin Pilot Super Sport · 225.70″ −0.02″
  26. Toyo Proxes Sport 225.70″ −0.02″
  27. Toyo Proxes Sport R25.70″ −0.02″
Each bar runs from the size code's 25.72″ (the orange line) to the model's published height. The track spans 1.0″. Where a model comes in several load ranges, the darker part shows its range of heights; the number after the name is how many versions it comes in.
Height under load24.9–25.2″

Published revs per mile (800–809) mean the tire rolls like a 24.9–25.2″ tire on the vehicle. Use this for speedometer calibration.

Weight spread21.9–28.1 lb

The lightest (General AltiMAX RT45, XL) is 6.2 lb lighter per corner than the heaviest (Michelin Pilot Super Sport, SL).

31 tires in 245/40R18

Sort by the spec you care about.

LoadRevs/miSource
General AltiMAX RT45TouringXL · 97V25.7021.911.01,609808Spec page
General AltiMAX365 AWTouringXL · 97V25.7021.911.01,609808Spec page
Michelin Pilot Sport Cup 2 ConnectPerformanceXL · 97(Y)25.7022.37.21,609809Spec page
Michelin Pilot Sport 4PerformanceXL · 97(Y)25.7023.49.51,609809Spec page
Toyo Proxes Sport 2PerformanceXL · 97(Y)25.7023.59.21,609808Spec page
Michelin Pilot Super SportPerformanceXL · 97Y25.7023.810.01,609809Spec page
Michelin Pilot Sport 4 SPerformanceXL · 97(Y)25.7023.99.51,609809Spec page
General G-MAX AS07PerformanceXL · 97W25.7024.010.01,609808Spec page
Michelin Pilot Alpin 5WinterXL · 97V25.7124.39.51,609809Spec page
Michelin CrossClimate2All-seasonXL · 97V25.7024.510.01,609809Spec page
Michelin Pilot Sport 3PerformanceXL · 97Y25.7024.68.51,609809Spec page
Michelin Pilot Sport 4PerformanceSL · 93Y25.7024.89.51,433809Spec page
General G-MAX RSPerformanceXL · 97Y25.7024.910.01,609808Spec page
Toyo Proxes R1RPerformanceSL · 93W25.9525.08.21,433800Spec page
BFGoodrich Advantage ControlAll-seasonXL · 97W25.7125.210.51,609809Spec page
Toyo Celsius IITouringXL · 97V25.7125.311.31,609808Spec page
Toyo Proxes Sport A/SPerformanceXL · 97Y25.7125.69.41,609808Spec page
Toyo Proxes Sport RPerformanceXL · 97W25.7025.67.21,609808Spec page
Michelin Pilot Sport All-Season 4PerformanceSL · 93(Y)25.7026.010.01,433809Spec page
Toyo Observe G3-IceWinterXL · 97T25.7126.011.31,609808Spec page
Michelin Pilot Sport All-Season 4PerformanceXL · 97Y25.9026.110.01,609804Spec page
BFGoodrich Advantage ControlAll-seasonXL · 97V25.7126.410.51,609809Spec page
BFGoodrich g-Force Phenom T/APerformanceXL · 97Y25.7126.89.01,609809Spec page
Michelin X-Ice SnowWinterXL · 97H25.7126.910.51,609809Spec page
BFGoodrich g-Force Rival+PerformanceSL · 93V25.7127.27.21,433809Spec page
BFGoodrich g-Force COMP-2 A/S PLUSPerformanceXL · 97Y25.7127.49.01,609809Spec page
BFGoodrich g-Force Rival SPerformanceSL · 93V25.7127.47.21,433809Spec page
Toyo Extensa HP IIPerformanceXL · 97W25.7127.69.61,609808Spec page
Toyo Proxes R888RPerformanceXL · 97Y25.7127.86.31,609808Spec page
Michelin Pilot Super SportPerformanceSL · 93(Y)25.7028.19.01,433809Spec page
General AltiMAX Arctic XWinterXL · 97T25.70–12.01,609808Spec page

Is 245/40R18 a 26-inch tire?

≈26″

Yes. The size code works out to 25.72″, and the 31 tires here publish 25.70–25.95″, so people call it a 26.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 245/40R18Difference
265/35R1825.30-0.41″-1.6%
235/40R1825.40-0.31″-1.2%
315/30R1825.44-0.28″-1.1%
275/35R1825.58-0.14″-0.5%
215/45R1825.62-0.10″-0.4%
285/35R1825.85+0.14″+0.5%
335/30R1825.91+0.20″+0.8%
225/45R1825.97+0.26″+1.0%
255/40R1826.03+0.31″+1.2%
295/35R1826.13+0.41″+1.6%

How to read 245/40R18

How to read any tire size

245/40R18 97Y as printed on the tire sidewall, with each part numbered245/40R18 97Y123456
How 245/40R18 97Y is printed on the sidewall. It's the most common code among the 31 tires here (8 of them); tires in this size come in other load and speed ratings too.
1245Section width

245 mm across the widest point, or 9.65 inches. Every 245 size

240Aspect ratio

A percentage, not a measurement: the sidewall is 40% as tall as the tire is wide, which is 98.0 mm or 3.86 inches.

3RConstruction

Radial construction.

418Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 8.0″ to 9.5″.

597Load index

Each tire carries up to 1,609 lb (730 kg) at its maximum pressure.

6YSpeed rating

Rated for up to 186 mph sustained.

XLExtra load

Printed after the size. In this size the XL tires carry up to 1,609 lb each and the standard-load tires up to 1,433 lb, as published.

SpecificationInchesMetric
Overall diameter25.72653 mm
Section width9.65245 mm
Sidewall height3.8698.0 mm
Circumference80.82,052 mm
Revolutions per mile (calculated, unloaded)784.2487 per km
Revolutions per mile (published by manufacturers)800–809497–503 per km
Approved wheel width8.0–9.5203–241 mm

Speedometer error after switching to 245/40R18

Your actual speed– mph

Questions about 245/40R18

What is 245/40R18 in inches?

25.72 inches tall, 9.65 inches wide, on a 18-inch wheel. Written in inches, that is roughly 25.7×9.6R18.

How much does a 245/40R18 tire weigh?

Between 21.9 lb and 28.1 lb for the 30 tires listed here. The lightest is the General AltiMAX RT45 (XL); the heaviest is the Michelin Pilot Super Sport (SL).

What wheel width do I need for 245/40R18?

Manufacturers approve 8.0–9.5″ wide wheels for this size.

How many revolutions per mile does a 245/40R18 make?

Published figures run 800–809 revolutions per mile. The calculated figure is 784.2, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 245/40R18 than 215/45R18?

0.10 inches taller on paper (25.72″ vs 25.62″), which raises the axle about 0.05″. Your speedometer will read about 0.4% slow.