2021 GMC Sierra 1500 tire size

Most common factory size

P275/60R20

Tire sizes by trim

Source marks: one source

2021 GMC Sierra 1500 tire size by trim
Size	Trims	Width, mm	Sidewall, % of width	Rim, in	Diameter, in	Sidewall, in	Revs per mile
P275/60R20	SLE Double Cab RWD, Elevation Double Cab RWD, SLE Crew Cab RWD, SLE Double Cab 4WD, Elevation Crew Cab RWD, Elevation Double Cab 4WD +12 more	275	60	20	32.99	6.50	611
P265/70R17	2WD Reg Cab 140", Double Cab RWD, 4WD Reg Cab 140", Crew Cab RWD, Double Cab 4WD, Crew Cab 4WD +1 more	265	70	17	31.61	7.30	638

What P275/60R20 means
Part	Number	Meaning
Type	P	Passenger car tire.
Width	275 mm	Tread width. 10.8 in.
Sidewall	60	Sidewall height is 60% 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 P275/60R20
Size	Rim, in	Diameter, in	Change	Speedo reads at 60 mph
255/65R20	20	33.05	+0.2%	59.9 mph
275/55R21	21	32.91	-0.3%	60.2 mph
265/60R20	20	32.52	-1.4%	60.9 mph
255/65R19	19	32.05	-2.9%	61.8 mph
255/60R20	20	32.05	-2.9%	61.8 mph

Sizes within 3% of P265/70R17
Size	Rim, in	Diameter, in	Change	Speedo reads at 60 mph
265/65R18	18	31.56	-0.1%	60.1 mph
265/75R16	16	31.65	+0.1%	59.9 mph
245/70R18	18	31.50	-0.3%	60.2 mph
245/75R17	17	31.47	-0.4%	60.3 mph
285/60R18	18	31.46	-0.4%	60.3 mph
235/80R17	17	31.80	+0.6%	59.6 mph
255/70R18	18	32.06	+1.4%	59.2 mph
255/75R17	17	32.06	+1.4%	59.2 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.