285/75R18 vs 35x12.50R20LT tire size comparison
35x12.50R20LT is 0.2 in (0.49%) taller than 285/75R18 and 1.3 in wider. They fit different wheels: 285/75R18 an 18-inch wheel and 35x12.50R20LT a 20-inch wheel.
285/75R18 and 35x12.50R20LT side by side
| Measurement | 285/75R18 | 35x12.50R20LT | Difference | Difference % |
|---|---|---|---|---|
| Section width | 11.2 in (285 mm) | 12.5 in (318 mm) | +1.3 in (+33 mm) | +11.40% |
| Sidewall height | 8.4 in (214 mm) | 7.5 in (191 mm) | -0.9 in (-23 mm) | -10.88% |
| Wheel (rim) diameter | 18.0 in (457 mm) | 20.0 in (508 mm) | +2.0 in (+51 mm) | +11.11% |
| Overall diameter | 34.8 in (885 mm) | 35.0 in (889 mm) | +0.2 in (+4 mm) | +0.49% |
| Circumference | 109.4 in (2779 mm) | 110.0 in (2793 mm) | +0.6 in (+14 mm) | +0.49% |
| Revolutions per mile | 579 | 576 | -3 | -0.48% |
Differences are 35x12.50R20LT minus 285/75R18; percentages are relative to 285/75R18. These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.
The overall diameter differs by 0.49%, 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 285/75R18, the actual speed on 35x12.50R20LT is about 60.3 mph. When it reads 60 mph on a vehicle built for 35x12.50R20LT, the actual speed on 285/75R18 is about 59.7 mph. These figures assume the speedometer is accurate on the original size and use nominal dimensions, so treat them as estimates.
| Speedometer reads | Actual on 35x12.50R20LT (built for 285/75R18) | Actual on 285/75R18 (built for 35x12.50R20LT) |
|---|---|---|
| 20 mph | 20.1 mph | 19.9 mph |
| 30 mph | 30.1 mph | 29.9 mph |
| 40 mph | 40.2 mph | 39.8 mph |
| 50 mph | 50.2 mph | 49.8 mph |
| 60 mph | 60.3 mph | 59.7 mph |
| 70 mph | 70.3 mph | 69.7 mph |
| 80 mph | 80.4 mph | 79.6 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.
285/75R18
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 calculatorShop for 285/75R18 or 35x12.50R20LT 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.
285/75R18
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 285/75R18
Side-by-side dimensions and speedometer difference for sizes close to 285/75R18 in overall diameter.
- 285/75R18 vs LT275/50R24-0.01% shorter than 285/75R18
- 285/75R18 vs 325/65R18-0.57% shorter than 285/75R18
- 285/75R18 vs LT305/55R22+1.09% taller than 285/75R18
- 285/75R18 vs LT315/70R17-1.35% shorter than 285/75R18
Other comparisons with 35x12.50R20LT
Side-by-side dimensions and speedometer difference for sizes close to 35x12.50R20LT in overall diameter.
- 35x12.50R20LT vs LT285/75R18-0.48% shorter than 35x12.50R20LT
- 35x12.50R20LT vs LT275/50R24-0.49% shorter than 35x12.50R20LT
- 35x12.50R20LT vs LT305/70R18-0.54% shorter than 35x12.50R20LT
- 35x12.50R20LT vs LT305/55R22+0.60% taller than 35x12.50R20LT
You might also need
- Digital tire pressure gauge (Amazon search, opens in a new tab)
Check your tire pressure against the number on your door placard.
- Portable tire inflator (Amazon search, opens in a new tab)
Top up a low tire at home without a trip to the gas station.
- Tire tread depth gauge (Amazon search, opens in a new tab)
Measure how much tread is left before you decide to replace.
- Lug wrench or torque wrench (Amazon search, opens in a new tab)
Useful for rotations and tire changes; follow the torque spec in your owner's manual.
Paid links to Amazon search results. As an Amazon Associate I earn from qualifying purchases. Read our affiliate disclosure.