Knowledge base
Fitment Guides
Practical guides for tire sizing, wheel offset, pressure, load index and the math behind safe fitment.
Tire size basics
Tire size basics
What Tire Size Difference Is Acceptable?
The 3% rule that pros use when plus-sizing or downsizing tires.
Tire size basics
Plus-Sizing Guide: How to Upgrade Wheel Size Safely
Plus-one and plus-two upgrades done right — keeping rolling diameter constant, picking the right tire width and offset, and knowing the comfort tradeoffs.
Wheel fitment
Wheel fitment
Wheel Offset & Backspacing Explained
ET, offset, backspacing — the difference between a perfect fitment and rubbing.
Wheel fitment
Can Bigger Wheels Damage Your Suspension?
What plus-sizing does to ride quality, bearings, and bushings.
Wheel fitment
Wheel Offset vs Backspacing: What Is the Difference?
Two ways of describing the same wheel geometry. Here is how offset (ET) and backspacing relate, when each is used, and how to convert between them.
Safety & load
Safety & load
Tire Pressure Explained: PSI, Load and Tire Size Changes
What PSI really means, why the door placard matters more than any online calculator, and how a tire size change can shift the right pressure.
Safety & load
Tire Load Index Explained: How Much Weight Can a Tire Carry?
Decode the number after your tire size — what kg per tire it represents, how it relates to speed rating, and why you must never go below the OEM rating.
Calculator guides
Calculator guides
How Speedometer Error Is Calculated
When you change tire size, your speedometer reading drifts. Here is exactly how the math works.