The Nitto Ridge Grappler in size 255/70R18 is a hybrid-terrain radial tire with a 116T service description. The Ridge Grappler is Nitto’s hybrid-terrain option, positioned between an all-terrain and a mud-terrain tire.
Size and wheel specifications
- Tire size: 255/70R18
- Manufacturer stock number: 217690
- Wheel diameter: 18 in
- Nominal section width: 255 mm
- Load index / speed rating: 116T
- Load designation: XL (Extra Load)
- Approved rim-width range: 6.5–8.5 in
- Measuring rim width: 7.5 in
- Manufacturer-listed overall diameter: 32.09 in
- Manufacturer-listed overall width: 10.24 in
- Tread depth: 13.5/32 in
- Maximum load / inflation rating: 2,756 lb at 50 psi
Nitto lists this exact stock number at 32.09 inches overall diameter and 10.24 inches overall width on the 7.5-inch measuring rim. The measuring rim is the reference for those published dimensions; the approved rim-width range is 6.5–8.5 inches.
Before ordering
Compare the complete size, load index and speed rating with your vehicle’s approved requirements. Confirm wheel width, wheel load capacity and clearance as well as diameter. A tire’s dimensions do not establish an OEM vehicle application. If changing tire size or type, have the combination and operating pressure checked by a qualified tire professional.
Questions about 255/70R18
What do the numbers in 255/70R18 mean?
The size uses a nominal 255 mm section width and an aspect ratio of 70; the sidewall height is expressed as a percentage of that nominal width. R denotes radial construction and 18 is the wheel diameter in inches. Nitto lists this exact tire at 32.09 inches overall diameter and 10.24 inches overall width on the 7.5-inch measuring rim.
What wheel width is approved for this 255/70R18 tire?
Nitto lists 6.5–8.5 inches as the approved rim-width range for stock number 217690. Its 7.5-inch measuring rim is the reference for the published dimensions, not the only approved width. The wheel must also have the correct 18-inch diameter and be suitable for the vehicle and required load.
What does the 116T XL marking tell me?
116 is the tire’s load index and T is its speed symbol. XL means Extra Load; it is a load designation, not a statement of the number of physical casing plies. Use the complete size and service description when checking a replacement against the vehicle’s approved requirements; the tire model name alone is not enough.
Is 50 psi the pressure I should run in this tire?
No. The listed 2,756 lb at 50 psi is Nitto’s maximum load/inflation rating. It is not a recommended pressure for every vehicle. Follow the applicable vehicle and tire guidance, and have the operating pressure confirmed when changing tire size, type or load requirements.
Will this 255/70R18 tire fit any vehicle with 18-inch wheels?
No. A matching 18-inch wheel diameter is only one requirement. Check the approved 6.5–8.5-inch rim-width range, complete 116T service description, wheel load capacity and vehicle clearance. The published 32.09-inch diameter is useful for comparison, but does not prove vehicle fitment or that a lift or modification is unnecessary.
