RightTread

Tire size

285/45R21 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 width285 mm11.22 in
Sidewall height128.3 mm5.05 in
Overall diameter789.9 mm31.1 in
Wheel diameter533.4 mm21 in
Circumference2482 mm97.7 in
Revolutions per mile649

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

Reading the marking

285 is the section width in millimetres, 45 is the sidewall height as a percentage of that width, R means radial construction, and 21 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 285/45R21 with another size →

285/45R21 tires at Tire Rack

All-season

TireLoad/speedPrice per tire
Pirelli Scorpion Zero All Season
Street/Sport Truck All-Season Truck		XL 113V$287.09View at Tire Rack
Pirelli Scorpion Zero Asimmetrico
Street/Sport Truck All-Season Truck		XL 113W$322.76View at Tire Rack

Highway / touring

TireLoad/speedPrice per tire
Yokohama Geolandar X-CV
Crossover/SUV Touring All-Season		XL 113W$368.99View at Tire Rack
Bridgestone Alenza Sport A/S
Crossover/SUV Touring All-Season		XL 113V$416.93View at Tire Rack

Summer performance

TireLoad/speedPrice per tire
Pirelli P Zero Run Flat (PZ4)
Max Performance Summer		XL 113Y$351.29View at Tire Rack
Goodyear Eagle F1 Asymmetric 5
Max Performance Summer		XL 113H$427.99View at Tire Rack

Winter

TireLoad/speedPrice per tire
Bridgestone Blizzak LM001 RFT
Performance Winter / Snow		XL 113V$246.71View at Tire Rack
Hankook Winter icept evo3 X
Light Truck/SUV Performance Snow Truck		XL 113V$282.61View at Tire Rack

Showing the lowest-priced in-stock options in each category from 46 285/45R21 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