2021 Porsche 911 tire size

Most common factory size

P245/35R20

Tire sizes by trim

Source marks: one source

2021 Porsche 911 tire size by trim
Size	Trims	Width, mm	Sidewall, % of width	Rim, in	Diameter, in	Sidewall, in	Revs per mile
P245/35R20	Carrera RWD, Carrera 4 AWD, Carrera S RWD, Targa 4 AWD, Carrera 4S AWD, Targa 4S AWD +1 more	245	35	20	26.75	3.38	754
P255/35R20	Turbo AWD, Turbo S AWD	255	35	20	27.03	3.51	746

What P245/35R20 means
Part	Number	Meaning
Type	P	Passenger car tire.
Width	245 mm	Tread width. 9.6 in.
Sidewall	35	Sidewall height is 35% of the width.
Construction	R	Radial tire.
Rim	20 in	Fits 20 in wheels.

Within 3% of the stock diameter. A common shop guideline, not a maker spec.

Sizes within 3% of P245/35R20
Size	Rim, in	Diameter, in	Change	Speedo reads at 60 mph
285/30R20	20	26.73	-0.1%	60.0 mph
245/40R19	19	26.72	-0.1%	60.1 mph
195/50R19	19	26.68	-0.3%	60.2 mph
275/35R19	19	26.58	-0.6%	60.4 mph
225/45R19	19	26.97	+0.8%	59.5 mph
275/30R20	20	26.50	-1.0%	60.6 mph
235/35R20	20	26.48	-1.0%	60.6 mph
255/35R20	20	27.03	+1.0%	59.4 mph

Sizes within 3% of P255/35R20
Size	Rim, in	Diameter, in	Change	Speedo reads at 60 mph
255/40R19	19	27.03	+0.0%	60.0 mph
225/45R19	19	26.97	-0.2%	60.1 mph
295/35R19	19	27.13	+0.4%	59.8 mph
305/30R20	20	27.20	+0.7%	59.6 mph
245/35R20	20	26.75	-1.0%	60.6 mph
265/35R20	20	27.30	+1.0%	59.4 mph
285/30R20	20	26.73	-1.1%	60.7 mph
235/45R19	19	27.33	+1.1%	59.3 mph

Checked against 292 factory sizes listed for 2009-2027 US models.

Tire pressure is on the driver door sticker. Not in this data.

Optional wheel packages may differ.