Tire Size and Fitment Explainer

Turns a tire size code, a vehicle, and the shop's fitment notes into a plain-English explanation the customer can follow.

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Before and after

BEFORE · what the owner typed

customer is Charles Tran, 2008 GMC Acadia silver. came in to Larkbrook Tire, 3869 Juniperbrook Rd, Ridgebank. phone 206-555-0154. he wants to know what his tires say and whether he can go bigger. tires on it now say 255/65R18 111S. door sticker says 255/65R18 111S too. he asked about 265/60R18 110H. tech Chen Velasquez checked it, says 265/60R18 is ok on the rim, no rubbing at full lock, overall diameter about 0.4 inch smaller than stock per the tech's chart. load index 110 is lower than the 111 on the sticker. fronts are 5/32 and rears are 3/32 tread. rear tires are two different brands. no prices yet.

AFTER · what the skill produced

Hi Charles,

Thanks for coming in to Larkbrook Tire with your 2008 GMC Acadia. You asked what your tire size means and whether you can go bigger. Here is what we found.

What your tire size means: 255/65R18 111S

255: the tire is 255 millimeters wide.
65: the sidewall height is 65 percent of the width.
R: radial construction.
18: it fits an 18 inch wheel.
111: the load index, which is the weight rating of one tire.
S: the speed rating.

Does it match your door sticker? Yes. Your door sticker says 255/65R18 111S, the same as the tires on the vehicle now.

The 265/60R18 110H you asked about: This size is 10 millimeters wider and has a shorter sidewall, and it fits the same 18 inch wheel. Chen Velasquez checked it and found it fits on your wheel with no rubbing at full lock. By our tech's chart, the overall height is about 0.4 inch smaller than your current tires. Its load index is 110, which is lower than the 111 on your door sticker.

Safety concern, recommended now

The 265/60R18 110H has a load index lower than your door sticker's 111. We do not recommend it for your Acadia.

Also recommended

Your rear tires are two different brands and are at 3/32 of tread. The front tires are at 5/32 of tread.

Checked and good

Your current size, 255/65R18 111S, matches your door sticker.
The 265/60R18 fits the wheel and clears at full lock, but see the load index note above.

Our recommendation: we recommend staying with 255/65R18 111S, the size on your door sticker, because the 265/60R18 110H has a lower load index than your door sticker. You decide what to do, and we will note anything you choose to decline.

Call us at 206-555-0154 and we will get you set up.

Larkbrook Tire, 3869 Juniperbrook Rd, Ridgebank

Questions for the owner

What are the prices and availability for 255/65R18 111S tires?
Does the tech recommend replacing the rear tires, and should they be quoted as a matched pair, given the two brands and 3/32 of tread?
Should the front tires at 5/32 of tread be quoted too?
Please confirm the door sticker and owner's manual before sending, and confirm any local rules on tire sizes.

What it does

Turns a tire size code, a vehicle, and the shop's fitment notes into a plain-English explanation the customer can follow. It explains what each number means, what the shop found for this vehicle, and which options the shop recommends.

Use it when: Use when a tire shop needs to explain a tire size, sidewall markings, or fitment options to a customer, such as "explain this tire size," "what do these numbers mean," "will this fit," or "write up the fitment options for the customer."