Remaining clearance to the strut or control arm
Inner clearance is usually tighter than outer clearance, and harder to inspect. Measure the current gap between the tire and the strut body or control arm, then subtract however far the new setup moves the tire's inner edge inward.
A workable margin at rest. Turn the wheel to full lock in both directions and check by hand — inner clearance can look fine straight ahead and contact only at lock.
Check at full steering lock, not just straight ahead. Inner clearance is usually at its worst with the wheel turned fully in one direction, which this static calculation cannot see.
Getting a number you can act on
- 01Measure the current inner gap yourself
Between the tire's inner sidewall and the nearest suspension component — usually the strut body — with the wheel straight and the vehicle at normal ride height. This requires actually looking behind the wheel, which is why it gets skipped.
- 02Get the inward movement figure
From the wheel fitment calculator's inner edge output, for a wheel or tire width and offset change.
- 03Read the remaining clearance
Again a static figure — with the wheel straight and the vehicle standing still.
- 04Turn the wheel to full lock, both directions, before finalising
Inner clearance problems overwhelmingly show up at full steering lock rather than with the wheel straight, which this static calculation cannot 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 − inward movementThe same subtraction as the fender clearance calculator, applied to the inner side of the wheel instead.
Why inner clearance gets missed more often than outer
Outer clearance is visible from outside the vehicle — anyone can glance at the gap between a tire and a fender lip. Inner clearance requires actually looking behind the wheel, at the strut body and control arm, which most people simply don't do until something has already made contact.
It is also frequently the tighter of the two. Modern strut and multi-link suspension designs pack components close to the wheel to maximise interior space and minimise unsprung weight, which leaves genuinely little room to spare on the inboard side compared to what is usually available toward the fender.
This is precisely why a wider wheel or a reduced offset — both of which move the wheel's position outboard, reducing inner clearance while sometimes appearing to improve outer clearance — deserves an inner-clearance check as seriously as the more visible outer one.
Suspension Clearance Calculator FAQ
How do I measure inner wheel clearance?+
With the wheel straight and the vehicle at normal ride height, measure the gap between the tire's inner sidewall and the nearest suspension component — typically the strut body.
Why is inner clearance often tighter than outer clearance?+
Modern suspension designs pack components close to the wheel to maximise interior space, leaving less room on the inboard side than is typically available toward the fender.
Does a lower offset wheel reduce inner clearance?+
Yes — lower offset moves the entire wheel outboard, which can improve outer (fender) clearance while simultaneously reducing inner clearance to the strut and control arm.
When does inner clearance contact actually happen?+
Overwhelmingly at full steering lock rather than with the wheel straight, which is why a static, straight-ahead measurement should always be followed by a full-lock check in both directions.
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.