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Tire size · 18-inch wheel · about 34.6x12.8R18

325/65R18 tire size

Overall diameter, nominal34.6 in

Estimate ±880 mm

A 325/65R18 tire is 34.6 in (880 mm) tall and 12.8 in (325 mm) wide on a 18-inch wheel, with a 8.3 in sidewall, and turns about 582 times a mile.

Stock on the Ram 1500 (2027), per their makers’ documents.

Width
12.8 in
Sidewall
8.3 in
Wheel
18 in
Revs per mile
582

01 / Dimensions

325/65R18 in inches and millimeters

What the size code works out to. A real tire of the size measures within about 1.5% of it, by brand, tread, wheel width and pressure.

325/65R18

Estimate ±
Overall diameter
34.6 in 880 mm34.1 to 35.2 in for real tires
Section width
12.8 in 325 mm
Sidewall height
8.3 in 211 mm
Wheel diameter
18 in 457 mm
Circumference
108.8 in 2,764 mm
Revolutions per mile
582 362 per km574 to 591

02 / Stock on

Vehicles that leave the factory on 325/65R18

Which configurations run it in which model years, printed the way each maker prints the size, and how it compares with the vehicle’s other stock sizes. A speedometer set for one of those reads off by the amount shown when you fit 325/65R18 instead.

  • Ram 1500Maker
    • 2027 · RHO, TRX SRTprinted 325/65R18

    Ram 1500 model years on 325/65R18:

    Its other stock sizes

    • 325/40R22 (2027 · Trim not specified with the Air suspension, with a package). 325/65R18 is 2.4 in taller: with a speedometer set for 325/40R22 it reads 6.9% low, 64.5 mph at an indicated 60.
    • 285/45R22 (2027 · Trim not specified). 325/65R18 is 2.5 in taller: with a speedometer set for 285/45R22 it reads 7.3% low, 64.7 mph at an indicated 60.
    • 275/65R18 (2027 · Tradesman, Big Horn / Lone Star with the Tire option 275/65R18, with a package). 325/65R18 is 2.6 in taller: with a speedometer set for 275/65R18 it reads 7.4% low, 64.8 mph at an indicated 60.
    • 305/50R20 (2027 · Trim not specified with the Tire option 305/50R20 (late availability), with a package). 325/65R18 is 2.6 in taller: with a speedometer set for 305/50R20 it reads 7.6% low, 64.9 mph at an indicated 60.
    • 275/55R20 (2027 · Tradesman, Limited; Big Horn / Lone Star, Laramie with the Tire option 275/55R20). 325/65R18 is 2.7 in taller: with a speedometer set for 275/55R20 it reads 7.9% low, 65.1 mph at an indicated 60.

Documents last checked . How we read them and what the marks mean: how we source the numbers. A figure doesn’t match its document? Report a wrong number.

03 / Nearby sizes

Sizes either side of 325/65R18

The nearest common upsizes and the next sizes down on the same wheel, from the stock sizes we cover and the sizes owners usually step up to, and sizes about as tall on another wheel.

Nearest sizes up

Nearest sizes up, compared with 325/65R18
SizeTallinHeightvs 325/65R18Widthvs 325/65R18At an indicated 60true mphCompare
285/75R1834.8+0.2 in−1.6 in60.359.4 to 61.2Compare →
35x12.50R1835.0+0.4 in−0.3 in60.659.7 to 61.5Compare →
37x12.50R1837.0+2.4 in−0.3 in64.163.1 to 65.1Compare →

Next sizes down

Next sizes down, compared with 325/65R18
SizeTallinHeightvs 325/65R18Widthvs 325/65R18At an indicated 60true mphCompare
295/70R1834.3−0.4 in−1.2 in59.458.5 to 60.2Compare →
265/75R1833.6−1.0 in−2.4 in58.357.4 to 59.2Compare →

About as tall, other wheels

About as tall, other wheels, compared with 325/65R18
SizeTallinHeightvs 325/65R18Widthvs 325/65R18At an indicated 60true mphCompare
315/75R1634.6±0.0 in−0.4 in59.959.0 to 60.8Compare →
315/70R1734.4−0.3 in−0.4 in59.558.6 to 60.4Compare →
35x12.50R1535.0+0.4 in−0.3 in60.659.7 to 61.5Compare →
35x12.50R1735.0+0.4 in−0.3 in60.659.7 to 61.5Compare →

04 / Next

Compare it with your size

Tire size calculator325/65R18 against 285/75R18, or any two sizes: height, speedometer and gearing.Compare sizesTire sizes by vehicleEvery stock size on the trucks and SUVs we cover.Browse sizesRam 1500 tiresStock tires and wheels by trim, and what bigger tires change on the Ram 1500.See the tires

05 / FAQ

Questions people ask

What is 325/65R18 in inches?

About 34.6x12.8R18: 34.6 in tall and 12.8 in wide on a 18-inch wheel.

Which vehicles come with 325/65R18 tires?

In our data: Ram 1500 (2027).

How does 325/65R18 compare with the Ram 1500’s other stock sizes?

325/65R18 is 2.4 in taller: with a speedometer set for 325/40R22 it reads 6.9% low, 64.5 mph at an indicated 60. 325/65R18 is 2.5 in taller: with a speedometer set for 285/45R22 it reads 7.3% low, 64.7 mph at an indicated 60. 325/65R18 is 2.6 in taller: with a speedometer set for 275/65R18 it reads 7.4% low, 64.8 mph at an indicated 60.

What is the next size up from 325/65R18?

285/75R18: about 0.2 in taller and 1.6 in narrower. On a speedometer set for 325/65R18 it reads 0.6% low (60.3 mph at an indicated 60).