Skip to main content
TireShopper

LT235/80R18 vs LT285/70R17 tire size comparison

LT235/80R18LT285/70R17

LT285/70R17 is 0.1 in (0.29%) shorter than LT235/80R18 and 1.9 in wider. They fit different wheels: LT235/80R18 an 18-inch wheel and LT285/70R17 a 17-inch wheel.

LT235/80R18 and LT285/70R17 side by side

-0.1 in / -0.29%LT235/80R18: 32.8 in tall, solid lineLT285/70R17: 32.7 in tall, dashed lineLT235/80R18Width 9.3 in (235 mm)Sidewall 7.4 in (188 mm)LT285/70R17Width 11.2 in (285 mm)Sidewall 7.9 in (200 mm)
LT235/80R18 is drawn with a solid line and LT285/70R17 with a dashed line. In each drawing both tires are to the same scale; the tread shoulder and bead curves are simplified. The table below has the same numbers.
Dimensions of LT235/80R18 and LT285/70R17, with the difference (LT285/70R17 minus LT235/80R18)
MeasurementLT235/80R18LT285/70R17DifferenceDifference %
Section width9.3 in (235 mm)11.2 in (285 mm)+1.9 in (+50 mm)+21.28%
Sidewall height7.4 in (188 mm)7.9 in (200 mm)+0.5 in (+12 mm)+6.12%
Wheel (rim) diameter18.0 in (457 mm)17.0 in (432 mm)-1.0 in (-25 mm)-5.56%
Overall diameter32.8 in (833 mm)32.7 in (831 mm)-0.1 in (-2 mm)-0.29%
Circumference103.1 in (2618 mm)102.8 in (2610 mm)-0.3 in (-8 mm)-0.29%
Revolutions per mile615617+2+0.29%

Differences are LT285/70R17 minus LT235/80R18; percentages are relative to LT235/80R18. These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.

The overall diameter differs by 0.29%, which is within the common 3% rule of thumb.

The rule of thumb keeps a replacement size within about 3% of the original overall diameter. It covers diameter only. It is not a fit, load or safety check, because width, wheel diameter, load capacity and clearance matter too. Confirm any size change with your vehicle's owner's manual or a tire professional.

Speedometer difference

When the speedometer reads 60 mph on a vehicle built for LT235/80R18, the actual speed on LT285/70R17 is about 59.8 mph. When it reads 60 mph on a vehicle built for LT285/70R17, the actual speed on LT235/80R18 is about 60.2 mph. These figures assume the speedometer is accurate on the original size and use nominal dimensions, so treat them as estimates.

Actual speed for a given speedometer reading, LT235/80R18 against LT285/70R17
Speedometer readsActual on LT285/70R17 (built for LT235/80R18)Actual on LT235/80R18 (built for LT285/70R17)
20 mph19.9 mph20.1 mph
30 mph29.9 mph30.1 mph
40 mph39.9 mph40.1 mph
50 mph49.9 mph50.1 mph
60 mph59.8 mph60.2 mph
70 mph69.8 mph70.2 mph
80 mph79.8 mph80.2 mph

A common rule of thumb is to keep a replacement size within about 3% of the original overall diameter. Check the tire placard on the driver's door jamb and your owner's manual for the sizes your vehicle was built for. Confirm any size change with your vehicle's owner's manual or a tire professional.

Which vehicles use each size?

These vehicles list the size among their verified sizes, by trim. Open one to see all of its sizes.

Check it in the calculator

The calculator takes the same two sizes and shows the full comparison, or lets you swap either one for another size.

Open this comparison in the calculator

Shop for LT235/80R18 or LT285/70R17 tires

Confirm the size on your tire sidewall or door placard first. These links open each store's own search; prices and stock are on their sites.

We may earn a commission if you buy through these links. It doesn't change the price you pay. Read our affiliate disclosure.

Other comparisons with LT235/80R18

Side-by-side dimensions and speedometer difference for sizes close to LT235/80R18 in overall diameter.

Other comparisons with LT285/70R17

Side-by-side dimensions and speedometer difference for sizes close to LT285/70R17 in overall diameter.

You might also need

Paid links to Amazon search results. As an Amazon Associate I earn from qualifying purchases. Read our affiliate disclosure.