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Tire size

255/55R20 tire size: dimensions explained

Factory size on the Porsche Cayenne (9YA facelift). 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 width255 mm10.04 in
Sidewall height140.3 mm5.52 in
Overall diameter788.5 mm31.04 in
Wheel diameter508.0 mm20 in
Circumference2477 mm97.5 in
Revolutions per mile650

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

Reading the marking

255 is the section width in millimetres, 55 is the sidewall height as a percentage of that width, R means radial construction, and 20 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 255/55R20 with another size →

255/55R20 tires at Tire Rack

All-season

TireLoad/speedPrice per tire
Radar Dimax AS-8
Grand Touring All-Season		XL 110W$161.33View at Tire Rack
BFGoodrich Advantage Control
Grand Touring All-Season		XL 110H$234.99View at Tire Rack

Highway / touring

TireLoad/speedPrice per tire
Advanta SVT Plus
Crossover/SUV Touring All-Season		XL 110V$168.59View at Tire Rack
Radar Renegade H/T Pro
Highway All-Season		XL 110H$170.70View at Tire Rack

All-terrain

TireLoad/speedPrice per tire
Bridgestone Dueler A/T RH-S
On-Road All-Terrain		107S$240.86View at Tire Rack
Nitto Nomad Grappler
On-Road All-Terrain		XL 110H$249.00View at Tire Rack

Summer performance

TireLoad/speedPrice per tire
Falken Azenis FK520
Street/Sport Truck Summer Truck		XL 110Y$260.03View at Tire Rack
Michelin Pilot Sport 4 SUV
Street/Sport Truck Summer Truck		XL 110Y$366.99View at Tire Rack

Winter

TireLoad/speedPrice per tire
Pirelli Scorpion Winter 2
Light Truck/SUV Performance Snow Truck		XL 110V$153.78View at Tire Rack
Vredestein Wintrac Pro+
Performance Winter / Snow		XL 110V$251.05View at Tire Rack

Showing the lowest-priced in-stock options in each category from 88 255/55R20 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

Other sizes