2003 GMC Sonoma — ZR2

The 2003 GMC Sonoma ZR2 came from the factory equipped with 31X10.50R15 tires. If your vehicle has since been fitted with aftermarket or upsized wheels, your actual tire size may no longer match this factory spec — always confirm against your door placard before buying.

31X10.50R15

Overall diameter31"
Section width10.5"
Rim diameter15"
Revolutions per mile~651

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What this size means for your GMC Sonoma

On the 2003 GMC Sonoma ZR2, the factory 31X10.50R15 is a flotation off-road size, quoted directly in inches rather than metric — about 31″ tall and 10.5″ wide on a 15″ wheel, turning roughly 651 revolutions per mile. Flotation sizes like this are chosen for traction and ground clearance rather than on-road refinement.

On a vehicle of this age, the GMC Sonoma 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 2003 GMC Sonoma trims

GMC Sonoma tire sizes by year

See every GMC Sonoma 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.