My Tire Guide

205/40R18 tire size

A 205/40R18 tire stands 24.5 inches tall and 8.1 inches wide, with a 3.2-inch sidewall on an 18-inch rim.

24.5″OVERALL 24.5 IN · RIM 18 IN8.1″3.2″WIDTH · SIDEWALL
Overall height
24.5 in621 mm
Section width
8.1 in205 mm
Sidewall height
3.2 in82 mm
Rim diameter
18 in457 mm
Circumference
76.8 in1952 mm
Revolutions per mile
825512 per km
Inch size
24.5x8.1R18

Compare it with any other size in the tire size calculator.

Sizes you can swap to

These 18-inch sizes are within two width steps and 3% of a 205/40R18's overall height, the usual limit before the speedometer, ABS and transmission notice. The closest is 185/45R18, 0.4% taller (0.10 in). Wider sizes also need room in the wheel well and a rim width that suits them.

SizeHeightWidthAt 60 mph
185/45R18+0.4%+0.10 in−20 mm60.2 mph
225/35R18−1.0%−0.26 in+20 mm59.4 mph
215/40R18+1.3%+0.31 in+10 mm60.8 mph
195/40R18−1.3%−0.31 in−10 mm59.2 mph
195/45R18+1.9%+0.45 in−10 mm61.1 mph
215/35R18−2.2%−0.53 in+10 mm58.7 mph
225/40R18+2.6%+0.63 in+20 mm61.5 mph
185/40R18−2.6%−0.63 in−20 mm58.5 mph

Plus and minus sizes

Changing rim size means changing the sidewall to keep the same overall height. On 16-inch or 17-inch or 19-inch rims, these are the closest matches to a 205/40R18.

SizeHeightWidthAt 60 mph
215/50R16+0.0%+0.01 in+10 mm60.0 mph
235/40R17−0.2%−0.06 in+30 mm59.9 mph
195/35R19−0.3%−0.08 in−10 mm59.8 mph

Other 18-inch sizes near 205/40R18

40 series, other widths

See the other sizes for this rim on 18-inch tire sizes.

Shop 205/40R18 tires

These open each store's own list of 205/40R18 tires, where you can filter by type, load and speed rating.

205/40R18 questions

How tall is a 205/40R18 tire?

About 24.5 inches (621 mm) from the ground to the top of the tread, unloaded. On the vehicle, carrying weight, it sits a little lower.

What does 205/40R18 mean?

205 is the section width in millimetres (8.1 in). 40 means the sidewall is 40% of that width: 82 mm, or 3.2 in. R means radial construction, and 18 is the rim diameter in inches.

Can I use 225/35R18 instead of 205/40R18?

225/35R18 is 1.0% shorter (0.26 in) and 20 mm wider, which is inside the usual 3% rule. With it fitted, the speedometer shows 60 mph when you are doing 59.4 mph. Make sure the extra width clears the suspension and fender liner at full lock.

What is 205/40R18 in inches?

In inch terms it is 24.5x8.1R18: 24.5 inches tall, 8.1 inches wide, for an 18-inch rim.

How many revolutions per mile does a 205/40R18 make?

About 825 turns per mile, worked out from its unloaded circumference of 76.8 inches. Makers list slightly higher numbers for their own tires, because a loaded tire rolls on a smaller radius.