Plus Size Calculator
Calculate plus-zero, plus-one, and plus-two tire and wheel sizing options. Find wider wheels and tires that maintain your original overall diameter.
How It Works
Enter your current tire size and wheel diameter. The calculator determines your original overall tire diameter, then searches through all standard tire sizes to find options that maintain the same diameter within a 3% tolerance.
Plus-zero: Same rim size, different width/aspect ratio.
Plus-one: Rim diameter increased by 1 inch.
Plus-two: Rim diameter increased by 2 inches.
Results are color-coded: green means within 1% of original diameter (ideal), yellow means 1-3% (acceptable), and red means over 3% (not recommended).
How to Read a Tire Size
A tire size like P265/70R17 breaks down as:
- P — Passenger tire (LT = Light Truck)
- 265 — Section width in millimeters
- 70 — Aspect ratio (sidewall height is 70% of width)
- R — Radial construction
- 17 — Rim diameter in inches
Flotation sizes like 33x12.50R15 use inches: 33" overall diameter × 12.5" width on a 15" rim.
Frequently Asked Questions
What is plus sizing for tires?
Plus sizing means increasing your wheel diameter while adjusting tire width and aspect ratio to maintain approximately the same overall tire diameter. Plus-one means going up 1 inch in rim size, plus-two means 2 inches up. This improves handling and aesthetics while preserving speedometer accuracy and ride quality.
How much diameter difference is acceptable when plus sizing?
Ideally, stay within 1% of your original tire diameter (shown in green). Up to 3% difference (yellow) is generally acceptable but may slightly affect speedometer accuracy. Anything over 3% (red) is not recommended as it will noticeably affect speedometer, odometer, and potentially ABS/traction control systems.
What are the benefits of plus sizing?
Plus sizing gives you a shorter sidewall and wider contact patch, which improves cornering response, steering precision, and braking grip. Larger wheels also allow bigger brake components and give a sportier appearance. The tradeoff is typically a firmer ride and more susceptibility to pothole damage.
Do I need to change anything else when plus sizing?
When going plus-one or plus-two, you need new wheels of the larger diameter. Check that the new tire and wheel combination fits your vehicle without rubbing on fenders, suspension, or brake components. Wheel width, offset, and bolt pattern must also be compatible with your vehicle.