What Rim Width Fits My Tire Size?

A common question is whether a 275 tire fits a wheel sold for a 265 tire. The numbers 265 and 275 are tire widths in millimeters, not wheel widths. Wheel rims are measured in inches. Discount Tire says a tire should fit within the rim width range approved by industry standards (TRA/ETRTO), so the way to check fitment is to compare your wheel width with the approved range for that tire size. The tire manufacturer or a tire shop can confirm the range for a specific tire.

What is a measuring rim width?

According to Tire Rack, the measuring rim width is the standardized wheel width on which a tire is mounted to establish its dimensions. Each tire size is assigned one measuring rim width, and Tire Rack notes it is also called the design rim width. Tire Rack explains that as section width increases, the measuring rim width increases proportionally in 1/2 in steps. The approved rim width range is separate from the single measuring rim width.

How does wheel width change tire section width?

Tire Rack explains that for every 1/2 in change in rim width, the section width of the tire changes by about 2/10 in. By formula, 0.5 in equals 12.7 mm calculated, and 0.2 in equals 5.1 mm calculated. On a narrower rim the tire becomes slightly narrower, and on a wider rim it becomes slightly wider. Tire Rack points out that this difference matters for clearance to fenders and suspension.

How do you calculate section width across approved rims?

Follow these steps to see section width on different rims.

Example: P205/60R15 on different wheel widths

1. Find the measuring rim. Tire Rack publishes a 6.0 in measuring rim for P205/60R15, with 8.23 in (209 mm) section width.
2. Check the approved range. Tire Rack lists an approved range of 5.5 to 7.5 in (139.7 to 190.5 mm calculated).
3. Apply the 0.2 in rule. On a 5.5 in rim, Tire Rack reports section width narrows to about 8.03 in.
4. Check the wider rims. Tire Rack reports about 8.43 in at 6.5 in, 8.63 in at 7.0 in, and 8.83 in at 7.5 in.
5. Find the total difference. Across that range, Tire Rack notes a total difference of 0.8 in (20.3 mm calculated).

Compare replacement dimensions with the tire size calculator.

Which rim widths fit common tire sizes?

The table below lists measuring rim widths from Tire Rack, plus the approved ranges that Tire Rack (P205/60R15) and Discount Tire (245/45R20) give as examples.

Discount Tire gives 245/45R20 as an example: the approved range covers wheels 20x7.5, 20x8.0, 20x8.5, 20x9.0, and 20x9.5. Discount Tire says the approved range follows industry standards (TRA/ETRTO).

How does rim width affect handling?

Discount Tire explains that a wider rim stretches the tire slightly and stiffens the sidewalls, which makes steering more direct and can reduce comfort. A narrower rim adds sidewall flex, which softens the steering response and can improve comfort. Discount Tire warns that a tire mounted outside its approved rim width range can show poor handling, irregular wear, and potential tire failure. Discount Tire also notes that rim width is measured between the bead seats. On a mounted wheel, you measure from outer edge to outer edge and subtract about 1 in. For example, Discount Tire gives 9.5 in measured outside as about 8.5 in of rim width. Review sidewall markings at how to read a tire sidewall. For wheel upgrades, see what tire size do I need for bigger wheels.

Frequently asked questions

Can I mount a 275 tire on a rim sold for a 265 tire?

The numbers 265 and 275 are tire widths in millimeters, while wheels are measured in inches, so they cannot be compared directly. What matters is whether your wheel width falls within the approved rim width range for the 275 tire size. The sources do not give a range for that size, so ask the tire manufacturer or a tire shop.

What happens if a wheel rim is too narrow or too wide?

Discount Tire says a tire should fit within the rim width range approved by industry standards. Outside that range, Discount Tire warns of poor handling, irregular wear, and potential tire failure.

How do I find the approved rim width for my tires?

Tire Rack publishes the measuring rim width and an approved range for the examples above, and Discount Tire refers to the TRA/ETRTO standards. For a specific tire, ask the tire manufacturer or a tire shop.

Sources

• Tire Rack: Measuring Rim Width
• Tire Rack: Rim Width Range
• Tire Rack: Section Width Determination
• Discount Tire: Measuring Rim Width