315/40R19 vs 295/45R18 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

315/40R19: 28.92″ (735 mm) tall, 12.40″ (315 mm) wide, sidewall 4.96″ (126 mm) — 697 revolutions per mile.

Within the usual 3% rule

−1.62% diameter

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

  • Needs 18″ wheels: this tire does not fit your 19″ rims.
  • 20 mm narrower: check the tire is approved for your rim width.

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Measurement315/40R19295/45R18Diff%
Overall diameter28.92″735 mm28.45″723 mm−0.47″−1.6%
Section width315.0 mm295.0 mm−20.0 mm−6.3%
Sidewall height126.0 mm132.8 mm+6.8 mm+5.4%
Rim diameter19″18″−1″−5.3%
Circumference90.86″2308 mm89.39″2270 mm−1.47″−1.6%
Revolutions per mileturns per distance; drives the odometer697433 /km709440 /km+11+1.6%
Ride height change——−0.23″ −6.0 mm

Speedometer reading

Speedo shows
60mph
97 km/h
Actual speed
59.0mph
95 km/h

Overlay

315/40R19295/45R18

Plus sizing: 315/40R19 on smaller or bigger wheels

Sizes fitted to cars that keep the overall diameter within 3% of 315/40R19 on a rim one inch smaller or up to two inches bigger, closest first.

RimSizeDiameterChangeCompare
R18 (−1) 285/50R18 29.22″ +1.0% Compare
295/45R18 28.45″ −1.6% Compare
R20 (+1) 325/35R20 28.96″ +0.1% Compare
285/40R20 28.98″ +0.2% Compare
R21 (+2) 335/30R21 28.91″ 0.0% Compare
285/35R21 28.85″ −0.2% 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 →