255/40R19 vs 265/35R20 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

255/40R19: 27.03″ (687 mm) tall, 10.04″ (255 mm) wide, sidewall 4.02″ (102 mm) — 746 revolutions per mile.

Well within tolerance

+1.00% diameter

The overall diameter changes by less than 1.5%, so speedometer error is negligible and ride height barely moves.

  • Needs 20″ wheels: this tire does not fit your 19″ rims.
  • 10 mm wider: check inner clearance and that your rims are wide enough.

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Measurement255/40R19265/35R20Diff%
Overall diameter27.03″687 mm27.30″694 mm+0.27″+1.0%
Section width255.0 mm265.0 mm+10.0 mm+3.9%
Sidewall height102.0 mm92.8 mm−9.3 mm−9.1%
Rim diameter19″20″+1″+5.3%
Circumference84.92″2157 mm85.78″2179 mm+0.85″+1.0%
Revolutions per mileturns per distance; drives the odometer746464 /km739459 /km−7−1.0%
Ride height change——+0.14″ +3.5 mm

Speedometer reading

Speedo shows
60mph
97 km/h
Actual speed
60.6mph
98 km/h

Overlay

255/40R19265/35R20

Plus sizing: 255/40R19 on smaller or bigger wheels

Sizes fitted to cars that keep the overall diameter within 3% of 255/40R19 on a rim one inch smaller or up to two inches bigger, closest first.

RimSizeDiameterChangeCompare
R18 (−1) 255/45R18 27.04″ 0.0% Compare
285/40R18 26.98″ −0.2% Compare
R20 (+1) 255/35R20 27.03″ 0.0% Compare
225/40R20 27.09″ +0.2% Compare
R21 (+2) 255/30R21 27.02″ 0.0% Compare
265/30R21 27.26″ +0.8% 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 →

Sizes often compared with 255/40R19