The Nitto Ridge Grappler in size 37X13.50R18LT is a hybrid-terrain radial tire with a 124Q 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: 37X13.50R18LT
- Manufacturer stock number: 217390
- Wheel diameter: 18 in
- Nominal section width: 13.5 in
- Load index / speed rating: 124Q
- Load designation: Load Range D (8-ply rating)
- Approved rim-width range: 9.0–11.5 in
- Measuring rim width: 11.0 in
- Manufacturer-listed overall diameter: 36.77 in
- Manufacturer-listed overall width: 13.58 in
- Tread depth: 18.3/32 in
- Maximum load / inflation rating: 3,525 lb at 50 psi
Nitto lists this exact stock number at 36.77 inches overall diameter and 13.58 inches overall width on the 11.0-inch measuring rim. The measuring rim is the reference for those published dimensions; the approved rim-width range is 9.0–11.5 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 37X13.50R18LT
Is this 37X13.50R18LT tire exactly 37 inches tall?
No. The 37-inch height and 13.5-inch width in the flotation size designation are nominal. Nitto lists stock number 217390 at 36.77 inches overall diameter and 13.58 inches overall width on its 11.0-inch measuring rim. The tire mounts on an 18-inch wheel.
What wheel width is approved for this 37X13.50R18LT tire?
Nitto lists 9.0–11.5 inches as the approved rim-width range for stock number 217390. Its 11.0-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.
Does Load Range D mean this tire contains 8 physical plies?
No. Load Range D corresponds to an 8-ply rating, a load/strength classification rather than a count of physical cord layers. This tire’s service description is 124Q. 124 is the load index and Q is the speed symbol. Match those requirements as well as the size.
Is 50 psi the pressure I should run in this tire?
No. The listed 3,525 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 37X13.50R18LT tire fit any vehicle with 18-inch wheels?
No. A matching 18-inch wheel diameter is only one requirement. Check the approved 9.0–11.5-inch rim-width range, complete 124Q service description, wheel load capacity and vehicle clearance. The published 36.77-inch diameter is useful for comparison, but does not prove vehicle fitment or that a lift or modification is unnecessary.
