Tire Tech

Tire Specs Explained: Rim Width Range for Street / Highway Tires

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Rim Width Range

Because tires have flexible sidewalls, a single tire size will fit on a variety of rim widths. A tire's rim width range identifies the narrowest to the widest rim widths upon which the tire is designed to be mounted during its tens-of-thousands of miles and years of service.

The width of the rim will influence the width of the tire. A tire mounted on a narrow rim would be "narrower" than if the same size tire was mounted on a wide rim.

Note: Because the overall diameter of a steel-belted radial is essentially determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.

The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".

"A tire's rim width range identifies the narrowest to the widest rim widths upon which the tire is designed to be mounted during its tens-of-thousands of miles and years of service."

For example, a tire in the P205/60R15 size is measured on a 6.0" wide wheel and this size tire has an approved rim width range from 5.5" to 7.5" wide. The tire has a section width of 8.23" (209mm) when mounted on a 6.0" wide wheel. If that tire were mounted on all of the rims within its range, the tire's approximate section width would change as follows:

Difference from Measuring Rim Rim
Width
Approximate Tire Section Width
0.5" narrower 5.5" 8.03"
Measuring Rim 6.0" 8.23"
0.5" wider 6.5" 8.43"
1.0" wider 7.0" 8.63"
1.5" wider 7.5" 8.83"

Because of the different wheel widths used in the above example, there is a 8/10" projected difference in tire section width when comparing a tire mounted on the narrowest rim to the widest rim within its range. This may affect fenderwell and frame clearances when selecting optional aftermarket wheel and tire packages.

Additionally, some vehicle manufacturers have developed Original Equipment applications in which the rim widths are not within the tire's original approved rim width range. For example:

1995 BMW M3 combined 235/40R17 sized tires on 17x7.5" rims (which are 0.5" less than the narrowest 8.0" wide rim listed for the size).

Corvette C3 models combined P225/70R15 sized tires on 15x8" rims (which are 0.5" wider than the 7.5" wide rim now listed for the size).

Corvette C4 models combined P255/50R16 sized tires on optional 16x9.5" rims (which are 0.5" wider than the 9.0" wide rim now listed for the size).

The rear tire application for Porsche 911 GT3 cars during 2010 - 2012 model years combined 305/30R19 sized rear tires on 19x12" rims (which are 0.5" wider than the 11.5" wide rim listed for the size).

While outside the normal recommended rim width ranges, these applications meet the specifications of the vehicle manufacturer.

Also read Tire Specs Explained: Rim Width Range for Track & Competition Use.


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