325/35R21 vs 325/30R23 tire size comparison

Change either size and everything below updates.

Start from your car make, model, year
Current tire size
/R
xR
New tire size
/R
xR

Width in mm · aspect = sidewall height as a % of width · rim in inches

Flotation (LT) sizes, all in inches: overall diameter × section width, then rim

325/35R21: 29.96″ (761 mm) tall, 12.80″ (325 mm) wide, sidewall 4.48″ (114 mm) — 673 revolutions per mile.

Within the usual 3% rule

+2.41% diameter

Most fitment guides accept up to 3%. Check clearance at full lock and full suspension compression before committing.

  • Needs 23″ wheels: this tire does not fit your 21″ rims.

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Measurement325/35R21325/30R23Diff%
Overall diameter29.96″761 mm30.68″779 mm+0.72″+2.4%
Section width325.0 mm325.0 mm0.0 mm0.0%
Sidewall height113.8 mm97.5 mm−16.3 mm−14.3%
Rim diameter21″23″+2″+9.5%
Circumference94.11″2390 mm96.38″2448 mm+2.26″+2.4%
Revolutions per mileturns per distance; drives the odometer673418 /km657409 /km−16−2.3%
Ride height change——+0.36″ +9.1 mm

Speedometer reading

Speedo shows
60mph
97 km/h
Actual speed
61.4mph
99 km/h

Overlay

325/35R21325/30R23

Plus sizing: 325/35R21 on smaller or bigger wheels

Sizes fitted to cars that keep the overall diameter within 3% of 325/35R21 on a rim one inch smaller or up to two inches bigger, closest first.

RimSizeDiameterChangeCompare
R20 (−1) 315/40R20 29.92″ −0.1% Compare
305/40R20 29.61″ −1.2% Compare
R22 (+1) 295/35R22 30.13″ +0.6% Compare
305/35R22 30.41″ +1.5% Compare
R23 (+2) 315/30R23 30.44″ +1.6% Compare
325/30R23 30.68″ +2.4% Compare

How to use the tire size calculator

Put your current tire size — width, aspect ratio and rim diameter — into the first form, then your desired size into the second. You’ll get the difference between the new and the old size, plus the speedometer reading difference and your actual speed on the new set. Both metric and flotation (LT inch) sizes are supported.

The calculator helps you decide whether a set of tires and wheels will fit your car. To compare tires by brand and model instead, use our tire comparison tool; to look up factory sizes, browse by car make.

Changing wheels too? The wheel offset calculator shows how far a new wheel width and offset move the tire toward the suspension and the fender.

Reading a tire size

225/45R17
225
Section width in millimetres
45
Aspect ratio — sidewall height as a % of width
R
Radial construction
17
Rim diameter in inches

Full guide to the tire sidewall →