Remaining outer clearance after a change
Measure the current gap between the tire and the fender lip yourself — that measured baseline is the only trustworthy starting point. This subtracts however far the new setup moves the tire's outer edge, giving what is actually left.
A comfortable margin at rest. Still check at full steering lock and full suspension compression, where clearance is always tighter than the static measurement.
This is a static calculation. Real clearance is always tighter at full steering lock and full suspension compression than it is with the vehicle sitting still. Confirm physically before finalising any tight fitment.
Getting a number you can act on
- 01Measure the current gap yourself
Between the tire's outer edge and the fender lip, with the vehicle sitting at normal ride height and the wheel pointed straight ahead. This baseline is the entire foundation of the calculation.
- 02Get the outward movement figure
From the wheel fitment calculator (a wheel or tire change) or the tire size comparison tool (a tire size change alone) — whichever change you're evaluating.
- 03Read the remaining clearance
This is the static figure — what's left with the vehicle standing still, wheel straight.
- 04Always verify dynamically before finalising
Turn the wheel to full lock in both directions and, if possible, check under suspension compression. Static clearance is always the most generous number you'll see.
What the calculator is actually doing
Nothing here is proprietary. If you would rather check it by hand, or explain it to someone at a counter, these are the same expressions the tool evaluates.
remaining = baseline measurement − outward movementSimple subtraction — the value of this tool is in being explicit about what the baseline requires (a real measurement) rather than in the arithmetic itself.
Why this tool insists on a measured baseline
Predicting absolute fender clearance from vehicle specifications alone is unreliable — factory tolerances, aftermarket suspension modifications, and even small variations in how a vehicle sits from side to side all mean the only trustworthy starting point is a measurement taken on the actual vehicle in front of you.
That is why this tool asks for a baseline rather than trying to calculate one. The value it adds is turning 'how much clearance is left after this change' into a straightforward subtraction, once you supply the one number that genuinely needs measuring.
The output is deliberately labelled as a static, at-rest figure. Real clearance is always tighter at full steering lock and under suspension compression than the standing measurement suggests, which is why the calculation here is a planning tool rather than a final verification.
Fender Clearance Calculator FAQ
How do I measure baseline fender clearance?+
With the vehicle at normal ride height and the wheel pointed straight ahead, measure the gap between the tire's outer sidewall and the fender lip directly.
Why does this need a measured baseline instead of calculating from scratch?+
Factory tolerances, suspension modifications and side-to-side variation make absolute clearance unreliable to predict from specifications alone — a real measurement on the actual vehicle is the only trustworthy starting point.
Is the calculated remaining clearance the real minimum?+
No — it's the static figure with the vehicle standing still and the wheel straight. Real clearance is always tighter at full steering lock and under suspension compression, so always verify physically before finalising a tight fitment.
Standards and references behind these figures
The arithmetic on this page is fixed, but the boundaries and conventions around it come from published standards and manufacturer guidance. These are the documents they come from, so you can check them rather than take them on trust.
01The Tire and Rim Association — standards filing (NHTSA docket)TRA has been the US standardising body for tire and rim interchangeability since 1903; this filing sets out dimensional practice.↗02TireGrades — minimum and maximum tire size for a given rim widthSummarises the approved rim-width range published for each section width by TRA and ETRTO.↗The wheel is only half the fitment. This calculates where the rim sits. The tire mounted on it reaches further out and further in than the rim does, and that rubber is what makes contact. Check the actual gaps at the strut and inside the fender, at full steering lock and full suspension compression, before ordering.