T155/90D17 Tire Size

T155/90D17 Spare Tire: The Tall-Sidewall Compact Spare Explained

T155/90D17 is a temporary spare tire with the same 155 mm width as T155/80D17 but a taller 90% aspect ratio sidewall - used when the vehicle's OEM tires are large enough that a shorter spare would create a problematic rolling circumference mismatch.

Among compact 17-inch spare tire sizes, T155/90D17 is one of the larger options, and it is fitted to specific vehicle models rather than being a universal spare. Always verify your vehicle's required spare size before purchasing a replacement.

T155/90D17 Quick Specs

What Each Part of the T155/90D17 Size Means

• T - Temporary-use tire
• 155 - Width in millimeters
• 90 - Aspect ratio (sidewall is 90% of section width)
• D - Diagonal (bias-ply) construction
• 17 - Wheel diameter

T155/90D17 vs T155/80D17: Same Width, Different Diameter

Both T155/80D17 and T155/90D17 tires are 155 mm wide and fit a 17-inch wheel. The difference is purely in sidewall height and, therefore, overall diameter:

Vehicles fitted with T155/90D17 have large enough original tires that the shorter T155/80D17 would create too great a diameter difference, potentially triggering stability control false alerts or causing differential stress in AWD vehicles during emergency use.

Does a Larger Compact Spare like T155/90D17 Mean You Can Drive It Further?

No. T155/90D17 is one of the physically larger compact spare sizes, but size does not extend the 50 mph / 60 psi / 50-mile limits that apply to all T-type tires. Those limits exist because of the tire's construction, rubber compound, and heat dissipation capacity - not its diameter. A T155/90D17 generates heat at the same rate as a smaller compact spare under load and speed, and its carcass is built to the same temporary-use standard. Drive directly to the nearest repair facility regardless of how substantial this spare looks compared to smaller donut sizes. Read our full guide on Spare Tire Limits for more details.