2025 Mercedes-Benz GLS tire size

Most common factory size

P275/45R21

Tire sizes by trim

Source marks: one source

2025 Mercedes-Benz GLS tire size by trim
Size	Trims	Width, mm	Sidewall, % of width	Rim, in	Diameter, in	Sidewall, in	Revs per mile
P275/45R21	GLS 450 4MATIC AWD	275	45	21	30.74	4.87	656
P285/45R22	GLS 580 4MATIC AWD	285	45	22	32.10	5.05	628

What P275/45R21 means
Part	Number	Meaning
Type	P	Passenger car tire.
Width	275 mm	Tread width. 10.8 in.
Sidewall	45	Sidewall height is 45% of the width.
Construction	R	Radial tire.
Rim	21 in	Fits 21 in wheels.

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

Sizes within 3% of P275/45R21
Size	Rim, in	Diameter, in	Change	Speedo reads at 60 mph
245/45R22	22	30.68	-0.2%	60.1 mph
275/50R20	20	30.83	+0.3%	59.8 mph
275/40R22	22	30.66	-0.3%	60.2 mph
285/40R22	22	30.98	+0.8%	59.6 mph
255/45R22	22	31.04	+0.9%	59.4 mph
295/45R20	20	30.45	-0.9%	60.6 mph
255/50R21	21	31.04	+1.0%	59.4 mph
255/55R20	20	31.04	+1.0%	59.4 mph

Sizes within 3% of P285/45R22
Size	Rim, in	Diameter, in	Change	Speedo reads at 60 mph
285/40R23	23	31.98	-0.4%	60.2 mph
275/50R21	21	31.83	-0.8%	60.5 mph
265/50R22	22	32.43	+1.0%	59.4 mph
275/45R22	22	31.74	-1.1%	60.7 mph
275/50R22	22	32.83	+2.3%	58.7 mph
295/40R22	22	31.29	-2.5%	61.5 mph
275/55R21	21	32.91	+2.5%	58.5 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.