TireSizeCalc

Load range and ply rating

LT tires show a load range letter, for example E. The letter replaced the older ply rating. Load range E is a 10-ply rating, but this does not tell you the number of plies.

Last reviewed · 7 source documents · Written in ASD-STE100 Simplified Technical English

What the load range letter is

FMVSS No. 139 tells manufacturers to mark the load range letter on each LT tire, with the maximum load rating.1 NHTSA tells you that the ply rating is an older system with the same function as the load range.2

“The ply rating is an older system which performed the same function now served by the load range.”

Quoted from the source 2
Load range and ply rating 3
Load rangePly rating
A2
B4
C6
D8
E10
F12
G14
H16
J18
L20
M22
N24

A ply rating is not a ply count

The sidewall must also show the actual number of plies in the sidewall, and in the tread area if it is different.4 The ply rating does not give this number. To find the number of plies, read the ply line on the sidewall.

Load range and load index

The load range letter does not give a load in pounds. The load index gives the load that the tire can carry.5 Read the load index on the sidewall. Then use the load index chart to convert it to pounds.

Many LT tires show two load indexes, for example 121/118. The first number is for one tire alone. The second number is for each tire when two tires are side by side (dual).56

When you replace LT tires

  1. Read the vehicle placard. Some placards show the load range and load index.7
  2. Read the load index on the tires that the vehicle maker installed.
  3. Do not select a new tire with a lower load index than the original tire. A lower index is a lower load.8
  4. Set the tires to the cold pressure on the vehicle placard.9

More guides

Printed from https://tiresizecalc.net/guides/load-range-ply-rating/. Figures as published on 2026-11-01. The sources are listed below.

Sources

  1. 49 CFR 571.139 - Standard No. 139; New pneumatic radial tires for light vehicles. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations (eCFR). 49 CFR 571.139. eCFR up to date as of 2026-10-15. S5.5(d). Retrieved 2026-11-01.
  2. Interpretation letter: ply rating and load range (to Federazione Italiana Fuoristrada). National Highway Traffic Safety Administration (NHTSA), Office of Chief Counsel. Undated on the web page. Letter text. Retrieved 2026-11-01.
  3. Toyo Tires 2024 Commercial Tires - Dimensions and Load Limits. Toyo Tire U.S.A. Corp. 2024-04-04. Ply rating and load range definitions. Retrieved 2026-11-01.
  4. 49 CFR 571.139 - Standard No. 139; New pneumatic radial tires for light vehicles. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations (eCFR). 49 CFR 571.139. eCFR up to date as of 2026-10-15. S5.5(f). Retrieved 2026-11-01.
  5. UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Para 2.27. Retrieved 2026-11-01.
  6. Commercial Tire Safety Tips. Federal Motor Carrier Safety Administration (FMCSA), US DOT. FMCSA-ADO-16-003. 2016-06. Sidewall marking diagram. Retrieved 2026-11-01.
  7. 49 CFR 571.110 - Standard No. 110; Tire selection and rims for motor vehicles with a GVWR of 4,536 kilograms (10,000 pounds) or less. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations, annual edition (GovInfo). 2006-10-01. S4.3(i). Retrieved 2026-11-01.
  8. UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Para 2.27 and Annex 4. Retrieved 2026-11-01.
  9. Tires (Tire Safety). National Highway Traffic Safety Administration (NHTSA). Undated web page. Tire pressure. Retrieved 2026-11-01.

Last reviewed 2026-11-01. The full source list, with dates and file checksums, is in How the numbers are calculated. To report an error, email contactus@tiresizecalc.net.