What Size Are 285/70R17 Tires? | Dimensions In Plain Numbers

285/70R17 tires measure roughly 32.7 inches in diameter and 11.2 inches wide, fitting 17-inch wheels.

The 285/70R17 size looks like code until you know the key: 285 is the width in millimeters, 70 is the sidewall height as a percentage of that width, and R17 means a radial tire for a 17-inch wheel. That works out to a tire that stands about 32.7–32.8 inches tall—solidly in the “33-inch class” even though it’s a hair under 33. If you’re shopping for a truck or SUV upgrade, here’s what each number means and what it tells you about fitment.

What Each Number In 285/70R17 Means

The three main figures break down into straightforward measurements. The section width is the widest point of the tire when mounted and inflated, and the overall diameter is the total height from the ground to the top of the tread.

• 285 — section width of 285 mm, or about 11.2 inches.
• 70 — aspect ratio of 70%, giving a sidewall height of roughly 7.9 inches.
• R — radial construction, which is standard for modern tires.
• 17 — the wheel diameter in inches.

A tire size calculator from 1010Tires confirms the overall diameter lands at 32.7 inches for this size, and tiresize.com lists the same figure at 32.8 inches depending on the specific model. The circumference runs about 102.7–103.0 inches, which translates to roughly 617 revolutions per mile.

Approved Wheel Widths For 285/70R17

This tire needs a 17-inch wheel, but the wheel width also matters. Most sizing charts approve these tires on 7.5–9.5 inch wide wheels for passenger versions, while LT versions typically approve 7.5–9.0 inch wheels.

The approved range exists because a tire’s actual footprint changes with rim width. A narrower wheel pinches the tire; a wider wheel stretches it. Both change handling, wear, and load capacity. Check the exact tire you’re buying and your vehicle’s specifications rather than assuming one rim width works for every tire in this size.

Why P-Metric And LT Versions Are Not The Same

The same nominal size can appear as P285/70R17 or LT285/70R17, and the difference matters for load and pressure. P-metric tires are built for passenger vehicles and SUVs; LT tires are built for light trucks with heavier loads. Even at the same physical size, their ratings diverge sharply.

One example listing shows a 285/70R-17 tire with Load Index 121/118, Load Range D (8-ply), a max speed of 106 mph (R rating), and a 65 psi inflation pressure. That’s a very different tire from a P-metric version with a 44 psi cap. The load index and load range printed on the sidewall must be checked against your vehicle’s placard—especially when comparing passenger and LT versions. If you’re looking for tires in this size for your truck or SUV, our roundup of top 285/70R17 tire picks covers the models worth considering.

Measurement Caveats That Matter In Real Life

The calculated specs assume a tire mounted on the approved rim width at its rated pressure. Actual dimensions vary by brand, tread design, and inflation. One manufacturer’s 32.7-inch tire might measure 32.8 inches on the same wheel, and a worn tire measures differently than a new one.

Tire size alone also doesn’t establish vehicle fitment. A 285/70R17 requires a 17-inch wheel, but you still need to confirm the wheel width falls within the approved range, and the tire needs sufficient clearance in the wheel well—especially at full steering lock and suspension travel. Load ratings matter just as much as dimensions. An LT tire at 50 psi is engineered for a different workload than a P-metric tire at 44 psi.

What all this means in practice: 285/70R17 is a 32.7-inch tire around 11.2 inches wide, designed for 7.5–9.5 inch wheels. Use those numbers as the starting point, then verify the specific tire model’s spec sheet and your vehicle’s requirements before buying.