2008 GMC Sierra — C1500 Crew Cab

The 2008 GMC Sierra C1500 Crew Cab shipped with 3 different factory tire sizes, depending on the wheel package it left the factory with (this can also reflect a staggered front/rear setup). Check your tire sidewall or door placard to confirm which one applies to your vehicle.

This trim shipped with more than one tire size (staggered fitment, front/rear, or optional wheel package). Confirm which one matches your vehicle by checking your tire sidewall or door placard.

245/70R17

Section width245 mm
Aspect ratio (sidewall height)70% (171.5 mm)
Rim diameter17"
Overall tire diameter~30.5"
Revolutions per mile~661

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265/70R17

Section width265 mm
Aspect ratio (sidewall height)70% (185.5 mm)
Rim diameter17"
Overall tire diameter~31.6"
Revolutions per mile~638

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275/55R20

Section width275 mm
Aspect ratio (sidewall height)55% (151.3 mm)
Rim diameter20"
Overall tire diameter~31.9"
Revolutions per mile~632

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What this size means for your GMC Sierra

On the 2008 GMC Sierra C1500 Crew Cab, the factory 245/70R17 measures about 30.5″ in overall diameter with a 171.5 mm (6.8″) sidewall, and completes roughly 661 revolutions per mile. Its 70-series aspect ratio gives a tall sidewall of the kind used on trucks, SUVs, and older passenger cars, built for cushioning and load. In tire terms it is a passenger (P-metric / Euro-metric) size.

The 245/70R17 and 265/70R17 differ in both width and overall diameter (1.1″, 3.6%), which usually means a staggered front/rear setup — the two sizes are not interchangeable side to side, so match each to its correct axle.

On a vehicle of this age, the GMC Sierra may have been refitted with a slightly different replacement size somewhere in its life, so check the current sidewall — not just the factory spec — before buying.

Other 2008 GMC Sierra trims

GMC Sierra tire sizes by year

See every GMC Sierra year & trim →

How to read a tire size

A tire size like 225/45R17 breaks down into three parts: the first number is the section width in millimeters (the tire's width from sidewall to sidewall), the second is the aspect ratio — the sidewall's height as a percentage of that width — and the number after the "R" is the rim diameter in inches. A letter prefix (P or LT) indicates Passenger or Light Truck construction; its absence usually means Euro-metric sizing.

Some trucks and off-road tires instead use "flotation" sizing, like 37X12.50R17 — here the numbers are the tire's overall diameter and width in inches directly, with the rim diameter last.

Always verify against the tire information placard on your driver's-side door jamb or your owner's manual before purchasing — tire size can vary by factory option package even within the same trim.