Calculate how much ground clearance changes when switching tire sizes. See the impact on ride comfort and scraping risk.
The ground clearance calculator analyzes the physical impact of tire size changes on the vertical distance between the vehicle's underbody and the road surface. Ground clearance is a critical metric affecting off-road capability, aerodynamic efficiency, and rollover stability due to changes in the center of gravity. This tool allows you to predict the lift or lowering effect achieved simply by changing tires, helping you determine the optimal setup for your vehicle's intended use.
The change in tire diameter is exactly twice the change in ground clearance. If the total tire diameter increases by 20mm, the axle center—and thus the vehicle—rises by 10mm from the road. The system calculates the diameter difference and divides it by two to derive the clearance change. Furthermore, it calculates the final expected ground clearance based on user-provided current data and provides insights into the engineering correlation between this value and approach/departure angles and underbody scraping risk.
Enter your current ground clearance and original/new tire sizes to calculate the change. Half the tire diameter difference equals the ground clearance change.
Increased clearance helps with off-road driving but raises the center of gravity, potentially reducing cornering performance.
Decreased clearance improves aerodynamics and cornering but increases the risk of scraping on speed bumps and steep driveways.
The clearance gain is exactly half the diameter change: clearanceChange = (newDiameter − oldDiameter) / 2. Worked example: moving from a 265/70R17 (797.4 mm) to a 285/70R17 (825.4 mm) adds (825.4 − 797.4) / 2 = 14 mm of static ride height. The most common error is expecting the full 28 mm diameter increase to appear at the axle, but only the radius change reaches the ground.
Tire-only lift never increases suspension travel or fender clearance, only the gap beneath the axle and differential. The lowest fixed point on most vehicles is the differential housing or skid plate, not the chassis, so a 14 mm tire lift raises those components by the same 14 mm. To clear larger tires you frequently still need a body or suspension lift to prevent rubbing at full compression.
Manufacturer diameters are unloaded; under vehicle weight the loaded radius compresses 2-3%, so a 825 mm tire may sit closer to ~808 mm effective diameter when stationary. For accurate planning, measure your existing static clearance with a ruler and add the calculated delta rather than trusting nominal numbers alone, since load, inflation pressure, and tread wear all reduce real clearance.