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How to Read Tires & Rims

A plain-English guide to the numbers and markings stamped on your wheels and tires — so you can list, shop, and buy with confidence.

1. Reading Rim Specifications

Rims (also called wheels) are described by a handful of key dimensions. Here's what each one means and why it matters when you're shopping.

Diameter (in)The distance across the wheel bead seat, measured in inches. This must match your tire's inner diameter. Common sizes: 15", 16", 17", 18", 20".
Width (in)The distance between the inner flanges where the tire bead sits, in inches. Tires should be ~0.5–1" wider than the rim for a proper mount.
Offset (mm)How far the mounting face sits from the wheel's centerline. Positive (+) pushes the wheel outward; negative (−) tucks it inward. Wrong offset = rubbing or suspension stress.
Center bore (mm)The hub hole diameter. Must be ≥ your vehicle's hub; hubcentric rings fill the gap for vibration-free mounting.
MaterialAlloy (lightweight, common), steel (durable, heavy), forged (strongest, lightest, priciest), chrome (plated finish).
ConditionNew, like-new, good, fair, or damaged — including curb rash, bent lips, cracks, and pitting. Always read the imperfection notes.
Why it matters: A wheel that's the wrong diameter, bolt pattern, offset, or bore simply won't fit your car — even if it looks right. Always cross-check these four specs against your vehicle's fitment.

2. Bolt Pattern (Lug Pattern)

Written as [number of lugs] × [pitch circle diameter in mm].

Example5×114.3 = 5 lug holes arranged on a circle 114.3 mm across.
Common patterns4×100, 4×108, 5×100, 5×114.3 (most common), 5×120, 6×139.7.

If you're unsure of your vehicle's bolt pattern, check your owner's manual or use a fitment guide — it's the single most important spec for compatibility.

3. Reading Tire Size

A typical sidewall reads something like P245/40R18 103Y. Here's how to break it down:

P (service type)P = passenger car; LT = light truck; T = temporary/spare; no letter = metric/Euro.
245 (section width)Tire width in millimeters at its widest point.
40 (aspect ratio)Sidewall height as a percentage of width. Lower = lower profile, stiffer ride. Here, 40% of 245 mm.
R (construction)R = radial (essentially all modern tires). D = diagonal/bias (rare).
18 (rim diameter)The wheel size the tire fits, in inches. Must match your rim diameter exactly.
103 (load index)A number mapping to max carrying capacity. 103 ≈ 1,929 lb per tire.
Y (speed rating)Max safe sustained speed. Common: H (130 mph), V (149), W (168), Y (186), (>190). Always match or exceed your vehicle's needs.
Tip: When replacing tires, match the size markings exactly unless you're intentionally changing fitment — a mismatched size throws off speedometer, handling, and clearance.

4. DOT Code & Manufacture Date

Look for the letters DOT on one sidewall, followed by 10–13 characters. The last 4 digits are the date code:

FormatWWYY — two-digit week (01–53) then two-digit year.
Example2319 = the 23rd week of 2019 (≈ June 2019).

DOT U2EE L1R 2319

First 6 chars = plant/size codes · last 4 (2319) = week 23, year 2019.

Tire age matters. Rubber degrades over time even with tread remaining. Most manufacturers recommend replacing tires older than 6–10 years regardless of wear, and never buy used tires more than ~6 years old.

5. Tread Depth (32nds of an inch)

Tread depth is measured in 32nds of an inch. New tires typically start at 10/32"–12/32". Here's a quick reference:

10/32" or moreExcellent — like new
6/32"–9/32"Good — safe in most conditions
4/32"–5/32"Fair — replace soon, weak in rain
Below 4/32"Low — should be replaced

On RimRevival, every tire listing must disclose its lowest measured tread depth so buyers know exactly what they're getting.

6. Tire Defects & Safety Checks

Always inspect used tires for these before listing or buying:

Bulges / blistersSidewall swelling — internal damage, do not use.
Cracking / dry rotFine splits in the rubber — age or UV damage.
Punctures / plugs / patchesPast repairs affect integrity and value.
Uneven wear / cuppingMisalignment or suspension issues.
Tread separationLayer peeling apart — dangerous, reject.
Flat spotsFrom skidding or sitting under load.
On RimRevival: Sellers must declare every tire as "all good" or disclose each defect with photos. Any undisclosed defect discovered later is grounds for a dispute under our return policy.

Ready to buy or sell?

Browse the marketplace or list your own wheels with full spec disclosure.

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