How to Read Tire Size: A Bulk Buyer’s Guide (2026)

When you buy one tire, a size mistake is a quick swap. When you buy hundreds in bulk, the wrong size is an expensive problem. Reading the sidewall correctly is a core skill for any dealer or distributor. This guide explains exactly what each part of a tire size means — for both passenger and commercial truck tires.

Anatomy of a passenger tire size

Take a common example: P215/65R15 95H. Each part has a meaning:

• P — tire class. “P” = P-metric (passenger). “LT” = light truck. No letter = Euro-metric.
• 215 — section width in millimetres (the tread width across the tire).
• 65 — aspect ratio: sidewall height as a percentage of width. Lower = shorter sidewall.
• R — construction. “R” = radial (the modern standard); “D” or “B” = bias-ply.
• 15 — rim (wheel) diameter in inches.
• 95 — load index: a coded figure for the maximum load the tire can carry.
• H — speed rating: a coded figure for the tire’s maximum rated speed.

Reading commercial truck tire sizes

Commercial sizes look a little different — for example 11R22.5:

• 11 — section width in inches (not millimetres, on this older sizing system).
• R — radial construction.
• 22.5 — rim diameter in inches.

Commercial tires also carry a load range (e.g. G, H, J) instead of a single load index — this reflects the ply rating and load/inflation capability. Always match the load range to the axle and application, and confirm the position the tire is built for: drive, steer, or trailer.

Load index and speed rating — don’t guess

Load index and speed rating are coded values that map to specific maximum loads and speeds in standardized industry tables. The exact load (in kg/lb) and speed (in km/h) for each code are published on those charts — check the tire’s own rating rather than estimating, especially for fleet and commercial use where compliance matters.

Other sidewall markings worth knowing

• DOT code — identifies the manufacturer and the week/year of production.
• M+S / 3PMSF — mud-and-snow and three-peak-mountain-snowflake (severe-snow) markings.
• Treadwear / traction / temperature — UTQG ratings on many passenger tires.
• Max load & max pressure — printed in full on the sidewall.

Why size accuracy matters in bulk

Ordering in volume magnifies every detail. A single transposed digit — 225 instead of 215, or R16 instead of R15 — can mean a whole pallet or container of tires you can’t sell to your customers. Before you place a bulk order, lock down the exact sizes your market demands and double-check them against the application. When you open a wholesale account, send us a clean size list and we’ll quote precisely against it.

Frequently asked questions

What does the R in a tire size mean?
It stands for radial construction — the modern standard. “D” or “B” indicates bias-ply.

What’s the difference between P-metric and LT tires?
“P” tires are built for passenger vehicles; “LT” (light truck) tires are built for heavier loads and have stronger construction.

How do I read a commercial truck tire size like 11R22.5?
11 = section width in inches, R = radial, 22.5 = rim diameter in inches. Pair it with the correct load range and wheel position.

Can TireBulk help me confirm the right sizes for my fleet or market?
Yes — send your vehicles, applications, or a size list and we’ll help match the right tires and quote them in bulk.

Order the right sizes, in bulk

Know your sizes? Send them over and we’ll quote wholesale pricing across commercial, agriculture, trailer, and specialty tires.

Request a wholesale quote →  ·  New buyer? Open a wholesale tire account.