Interpret a commercial C tire-size suffix and distinguish it from load range C

The short answer

A C that appears immediately after the rim diameter in a tire size, as in 225/65 R 16 C, marks the tire as a reinforced commercial tire, the kind typically fitted to vans. A C that appears in a separate field labeled load range belongs to that field instead. Load range relates to the tire's ply rating, not to the size. The two can appear on the same sidewall, but they are different fields, and you should not transfer the meaning of one to the other just because they use the same letter.

Neither C tells you how much weight a particular tire carries or whether it fits your vehicle. Carrying capacity comes from the documented load information, starting with the load index in the service description. Approved sizes for a given van come from the vehicle manufacturer's owner's manual.

How the commercial C fits into a full size marking

Michelin uses the complete marking 225/65 R 16 C 112/110 R as an example of a van tire size. Reading it left to right shows where the commercial C sits and why it cannot be confused with the other letters once you know each field's position.

225/65 R 16 C 112/110 R
         |  | |       |
         |  | |       +-- speed rating (R)
         |  | +---------- load indices (112/110)
         |  +------------ commercial / reinforced designation (C)
         +--------------- radial construction (R)
           16 = rim diameter

This example contains two R characters, and they mean different things. The first R, before the rim diameter, denotes radial construction. The final R, after the load indices, is the speed rating. The C sits between the rim diameter and the load indices. It is neither the load index nor the speed rating.

Michelin gives a second example, 215/65 R 16 C 109/107 T. The structure is the same: the C follows the rim diameter, the load indices follow as two numbers separated by a slash, and the speed symbol, T in this case, comes last. Michelin describes C-marked van tires as having reinforced carcasses, meaning the tire's internal structure is built for commercial use.

What load range means and where it appears

Continental's guidance on reading sidewalls treats three items as separate fields: the tire size, the load range and the service description. Load range corresponds to ply rating, which is an indicator of the tire's construction strength. Continental notes that carrying capacity depends on several factors, of which load range is one, so a load range letter alone is not a capacity figure.

The service description is the group of characters containing the load index and the speed symbol. On Continental's commercial tires it appears near the size. In the Michelin examples, it is the 112/110 R or 109/107 T portion at the end of the marking.

Field	Where it appears	Example	What it tells you
Commercial size suffix	Directly after the rim diameter, inside the size	16 C	Reinforced commercial (van) tire designation
Load range	A separate, explicitly labeled field	LOAD RANGE C	Load range, which corresponds to ply rating
Load index	Service description, after the size	112/110	Load indices used to determine carrying capacity
Speed symbol	End of the service description	R or T	Speed rating

How to read the sidewall and record each C correctly

Work from the sidewall itself or a clear photo of it, not from memory or a shortened listing. Write the complete marking exactly as printed before you interpret anything.

• 1. Find the size string and copy it in full, including every letter and number up to and including the speed symbol.
• 2. Locate the rim diameter, which is the number after the first R. If a C sits directly after it and before the load indices, record it as the commercial size suffix. Compare the string with the Michelin examples 225/65 R 16 C 112/110 R and 215/65 R 16 C 109/107 T to confirm the position matches.
• 3. Look elsewhere on the sidewall for a field explicitly labeled load range. If it contains a C, record it separately as the load range. Do not merge it with the size suffix.
• 4. Identify the service description: the load indices and the speed symbol that follow the size. Record the load indices and the speed symbol as their own entries.
• 5. For carrying capacity, use the documented load information for the tire, beginning with the load index. Do not assign a capacity based on either C.
• 6. For fitment, check the sizes approved in your vehicle manufacturer's owner's manual. A matching C designation does not establish that a tire is approved for your van.
• 7. Completion check: every occurrence of C on your notes should be assigned to exactly one named field, and the load indices and speed symbol should be recorded independently of both.

A simple worksheet for transcribing markings

If you are comparing several tires, a transcription worksheet keeps each occurrence of the letter tied to its field. Use these columns: manufacturer and model, complete marking, occurrence of C, characters on either side of it, identified field, matching manufacturer example and interpretation. Give each separate occurrence of C its own row.

Illustrative example: suppose a transcription shows a size ending in 16 C and, elsewhere on the sidewall, a field labeled LOAD RANGE C. On the worksheet, the first C goes in a row identified as the commercial size suffix, matched to the Michelin size examples. The second C goes in a separate row identified as load range. Capacity is then taken from the tire's documented load information, not assigned to either letter, and not assumed to be shared between them.

Common mistakes to avoid

• Treating the size-suffix C as a load range: its position after the rim diameter places it inside the size, not in a labeled load-range field.
• Reading the C as a speed rating or load index: in the Michelin examples, those values follow the C as separate characters.
• Confusing the two R characters: the one before the rim diameter means radial, while the one at the end of 225/65 R 16 C 112/110 R is the speed rating.
• Using a C to estimate how much weight a tire can carry: capacity comes from the documented load information, and load range is only one factor in it.
• Assuming a C-marked tire fits any van: approved dimensions for a specific vehicle come from its manufacturer's manual.