From The Tirerack website:
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 that the tire is designed to fit. 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 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".
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.......Rim..........Approximate Tire
Measuring Rim........Width..........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 and tire companies have permitted
rim widths that are not within the tire's original approved rim width range. For
example: BMW has 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) on certain M
models; and Chevrolet has combined P255/50R16 sized tires on optional 16x
.5" rims (which are 0.5" wider than the 9.0" wide rim now listed for the size)
on certain Corvette models. While these applications have received the
approval of the vehicle and tire manufacturers, staying within the approved
rim width range helps assure that the tire's internal stresses are within its
design parameters.
Measuring Rim Width
The measuring rim width is the industry standardized rim width upon which
the tire must be mounted in order to confirm it meets its dimensional targets.
Because the width of the rim will influence the width of the tire, a standard
rim width for every tire size is assigned and must be used. This standardized
measuring rim width allows all of the tires produced around the world to meet
the same dimensional standards and therefore, be equivalent with regards to
their physical size. The measuring rim width is sometimes referred to as the
tire's "design rim width".
The assigned measuring rim width changes with the tire size's section width
and with the tire size's aspect ratio. As tire section width increases, the
measuring rim width increases proportionately in 1/2" increments. Therefore,
relatively narrow wheel widths are assigned for smaller tires while wider wheel
widths are assigned for larger tires.
Tire Size..........Measuring Rim Width
P175/75R14...............5.0"
P195/75R15...............5.5"
P215/75R15...............6.0"
P235/75R15...............6.5"
Additionally, relatively "narrow" measuring wheel widths are assigned for taller
profile tires (75-series sizes) which graduate in 1/2" increments to the wider
wheel widths assigned for lower profile tires (40-series sizes)
Tire Size..........Measuring Rim Width
P225/75R15...............6.0"
P225/70R15...............6.5"
P225/65R16...............6.5"
P225/60R15...............6.5"
P225/55R15...............7.0"
P225/50R15...............7.0"
P225/45R17...............7.5"
P225/40R18...............8.0"
See the whole page here .
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 that the tire is designed to fit. 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 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".
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.......Rim..........Approximate Tire
Measuring Rim........Width..........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 and tire companies have permitted
rim widths that are not within the tire's original approved rim width range. For
example: BMW has 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) on certain M
models; and Chevrolet has combined P255/50R16 sized tires on optional 16x
.5" rims (which are 0.5" wider than the 9.0" wide rim now listed for the size)
on certain Corvette models. While these applications have received the
approval of the vehicle and tire manufacturers, staying within the approved
rim width range helps assure that the tire's internal stresses are within its
design parameters.
Measuring Rim Width
The measuring rim width is the industry standardized rim width upon which
the tire must be mounted in order to confirm it meets its dimensional targets.
Because the width of the rim will influence the width of the tire, a standard
rim width for every tire size is assigned and must be used. This standardized
measuring rim width allows all of the tires produced around the world to meet
the same dimensional standards and therefore, be equivalent with regards to
their physical size. The measuring rim width is sometimes referred to as the
tire's "design rim width".
The assigned measuring rim width changes with the tire size's section width
and with the tire size's aspect ratio. As tire section width increases, the
measuring rim width increases proportionately in 1/2" increments. Therefore,
relatively narrow wheel widths are assigned for smaller tires while wider wheel
widths are assigned for larger tires.
Tire Size..........Measuring Rim Width
P175/75R14...............5.0"
P195/75R15...............5.5"
P215/75R15...............6.0"
P235/75R15...............6.5"
Additionally, relatively "narrow" measuring wheel widths are assigned for taller
profile tires (75-series sizes) which graduate in 1/2" increments to the wider
wheel widths assigned for lower profile tires (40-series sizes)
Tire Size..........Measuring Rim Width
P225/75R15...............6.0"
P225/70R15...............6.5"
P225/65R16...............6.5"
P225/60R15...............6.5"
P225/55R15...............7.0"
P225/50R15...............7.0"
P225/45R17...............7.5"
P225/40R18...............8.0"
See the whole page here .
