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Tire size

325/65R18 tire size: dimensions explained

Factory size on the Ram 1500. Below are the dimensions calculated from the size marking itself. Your vehicle's correct size, load index and speed rating are on the placard in the driver's door jamb; check it before buying.

MeasurementMetricImperial
Section width325 mm12.8 in
Sidewall height211.3 mm8.32 in
Overall diameter879.7 mm34.63 in
Wheel diameter457.2 mm18 in
Circumference2764 mm108.8 in
Revolutions per mile582

Calculated values: diameter = wheel + 2 × (width × aspect ratio). Real tires vary slightly by brand and model.

Reading the marking

325 is the section width in millimetres, 65 is the sidewall height as a percentage of that width, R means radial construction, and 18 is the wheel diameter in inches. A passenger (P or Euro-metric) tire and an LT tire in the same size are not interchangeable without checking load requirements.

Compare 325/65R18 with another size →

325/65R18 tires at Tire Rack

All-terrain

TireLoad/speedPrice per tire
Goodyear Wrangler Territory AT
On-Road All-Terrain		D 121/118T$397.99View at Tire Rack
Falken WildPeak A/T4W
Off-Road All-Terrain Truck		D 121/118T$398.00View at Tire Rack

Rugged / mud-terrain

TireLoad/speedPrice per tire
Goodyear Wrangler Territory RT
Rugged All-Terrain		D 121/118Q$366.84View at Tire Rack

Showing the lowest-priced in-stock options in each category from 3 325/65R18 tires in Tire Rack's feed, sorted by price only. We don't rank by commission. Match or exceed the load index and speed rating on your placard.

Affiliate links: if you buy through a Tire Rack link, RightTread may earn a commission through CJ. It doesn't change your price. Prices are Tire Rack's per-tire prices from Tire Rack's product feed as of Nov 7, 2026, 9:19 PM PT. Prices change, so confirm on Tire Rack before you buy. Disclosure

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