Compare tire dimensions, calculate speedometer error, ground clearance changes, and check fender clearance before upgrading or changing tire sizes.
| Measurement | Current | New | Difference |
|---|---|---|---|
| Section Width | -- | -- | -- |
| Sidewall Height | -- | -- | -- |
| Overall Diameter | -- | -- | -- |
| Circumference | -- | -- | -- |
| Revs per Mile | -- | -- | -- |
| Speedometer Shows | Actual Speed |
|---|
Essential tools for safe tire changes and maintenance
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Plus-sizing means increasing rim diameter while decreasing sidewall height to maintain similar overall tire diameter. Benefits include improved handling, better cornering grip, and enhanced appearance. The trade-offs are typically a firmer ride, increased road noise, and higher cost. Plus-one means going up one inch in rim size, plus-two means two inches, etc.
Your speedometer measures wheel rotations and assumes factory tire size. Larger tires travel farther per rotation, so your actual speed is higher than displayed (speedometer reads slow). Smaller tires mean your actual speed is lower than displayed (speedometer reads fast). A 3% diameter increase means at an indicated 60 mph, you are actually traveling about 62 mph.
Load rating indicates the maximum weight each tire can safely carry. It is shown as a number after the size (e.g., 225/65R17 102H). Never choose tires with a lower load rating than your originals. This is especially critical for trucks, SUVs, and vehicles that carry heavy loads. The load rating must meet or exceed your vehicle's requirements for safety.
Yes, larger and wider tires typically reduce fuel economy due to increased weight, rolling resistance, and aerodynamic drag. Expect 1-2 mpg reduction with significantly larger tires. However, the effect varies based on tire construction, tread pattern, and driving conditions. Low rolling resistance tires can offset some of this penalty.
Before installing larger tires: 1) Measure current clearance between tire and fender at rest and with suspension compressed, 2) Account for steering (tires move inward when turned), 3) Check clearance at inner fender liner and suspension components, 4) Consider driving conditions - loaded vehicles and rough roads compress suspension more. A general rule is to have at least 1 inch clearance with suspension fully compressed.