|
|
|
CUSTOMIZING
PLUS SIZING
"Inch Up" To Plus Zero, Plus One &
Plus Two Tire Size Applications
|
|
What's "Inch Up"?
"Inch Up" is the process of mounting a lower aspect ratio tire
and larger diameter wheel on your car. This creates a larger
contact patch and a shorter sidewall.
|
Why "Inch Up"?
"Inch Up" to improve your vehicle's performance and appearance.
- Increased Steering Response
- Improved Dry Handling
- Enhanced Cornering Ability
- Aggressive Good Looks
|
"Inch Up" may be done in several ways.
The most popular are:
"Inch Up" to improve your vehicle's performance and appearance.
- Plus Zero
This method utilizes the same wheel diameter as OE, but
incorporates a tire with a larger than OE section width
and smaller than OE aspect ratio. For example, replacing
an OE 175/70R14 tire (on a 5.5-inch wheel) with a
195/60R14 tire would be a proper Plus Zero fitment. Note
that this may require a replacement wheel to maintain
proper rim width for the new tire.
- Plus One
This method utilizes a one-inch larger diameter wheel,
in conjunction with a tire of a one-step lower aspect
ratio. An example of an appropriate Plus One fitment is
to replace an OE 175/70R13 tire (23-inch overall diameter)
with a 185/60R14 tire (22.9-inch overall diameter). Note
that this method always requires a replacement wheel.
- Plus Two
This method utilizes a two-inch larger diameter wheel, in
conjunction with a tire of a two-step lower aspect ratio. An
example of an appropriate Plus Two fitment is to replace an
OE 175/70R13 tire (23-inch overall diameter) with a 195/50R15
tire (22.8-inch overall diameter).
|
An independent research company recently conducted a test to
determine the effect Inch Up has on handling. Included here is an
abbreviated summary of the test results.
The vehicle used for this comparison was a 1989 Mazda RX-7 SE.
The original equipment tire is a 185/70HR14, and is mounted on a
5.5-inch wide wheel. The test was conducted on a dry asphalt
surface. As the results from the lateral acceleration and
handling course indicate, each successive plus size led to a
noticeable increase in handling performance.
This fitment guide recommends several Inch Up applications for
both import and domestic vehicles. If the desired Inch Up
application is not listed, the guidelines listed on the next page
should be utilized to evaluate its appropriateness.
|
Warning:
When changing to a non-OE tire size, always consult the
load/inflation charts to determine proper inflation pressure
to maintain OE load-carrying capacity.
|
 |
|
|
|
|
|
|