GRAN TOCINO
Wheel & tire fitment

Fitment Bench

Compare a new wheel and tire against a baseline, either a car's factory setup or any wheel you choose. See how far it moves inboard and outboard, and how much room is left once you enter measured gaps.

Compare against

Suspension & alignment

What these settings do
Suspension:
sets how each axle is drawn and which parts move when camber changes. The car's own layout is marked "(stock)".
Camber adjusted by:
camber bolts and arm or link adjustments lean the knuckle and wheel while the strut or shock stays put. Camber plates and offset ball joints tip the whole strut with the wheel, so strut clearance holds. The usual method for the car is marked "(typical)".
Front KPI:
kingpin inclination (also called SAI), the inward lean of the steering axis. Many alignment machines can report it. 13° is a typical default for cars like these. It sets the strut angle and the tire-diameter part of the scrub radius change.
Stock scrub:
optional. Enter the real number if you find it, and the cards show absolute scrub radius as well as the change.

Hub measurements

mm, wheel off, optional

Measure with the suspension loaded. Take the wheel off, then jack the hub or lower arm back up to ride height. Zero is the hub face, where the studs come through the rotor hat.

How to measure

Step-by-step measuring guide with drawings →

Inboard:
lay a straightedge across the hub face and measure inward to the first thing the tire or the rim's barrel could hit: strut body, spring perch or upper arm. Measure at the height of the rim's edge and above, about half the wheel diameter up from the hub center (about 216 mm / 8.5 in for a 17" wheel). The middle of the wheel, the spokes and center, is dished outboard and won't reach a part beside the hub, so only the barrel and the tire matter here. Brake and caliper clearance to the spokes is a separate check.
Fender lip:
hang a plumb line or straightedge down from the fender lip and measure outward from the hub face to it.
Arch:
hub center straight up to the fender arch.
Ride height:
measure the arch first with the car on the ground. Once the wheel is off, jack the hub or lower arm back up until the arch number matches, so the suspension isn't hanging at full droop for the other two.
Camber when measured:
the alignment the car had when you measured, read off an alignment sheet. 0° is true vertical. It tilts the baseline wheel in the drawing and is the starting point for the camber sliders.
Safety buffer:
every gap must leave at least this much room to show Clear or Tight. Real tires differ from their nominal size, sidewalls bulge and tires grow at speed, so a 13 mm space is never treated as room for a 13 mm-wide wheel and tire. Inside the buffer shows Too close; past the measured line shows Hits.
Saved per car in this browser.
New tire New wheel Baseline outline Hub face Suspension, brakes, fender (illustrative) Front view of the passenger side. Outboard is left, inboard is right.

Spacers & studs

for the new setup
Stud check
How spacers and studs are checked
Room for a spacer:
a spacer moves the whole wheel outboard by its thickness. That adds the same amount to the inboard gap and takes it away from the fender lip. The range is every thickness that keeps both gaps at or past the safety buffer, with the new wheel at its camber. It is a static, ride-height check: bumps, body roll and steering lock need more room.
Sizes:
common sizes are listed. Click one to put it in the New setup's spacer box. Green fits, amber is tight, red doesn't fit as-is. Red sizes show how much more room they need at the fender lip to keep the safety buffer: "10 mm · +8" means rolling, pulling or flaring the lip out at least 8 mm, or adding enough negative camber to tuck the tire 8 mm. The colors follow the camber sliders, so you can watch a size turn amber or green as you add camber. Sizes marked "inboard" are too close on the inside; fender work won't fix that, a thicker spacer or less negative camber will.
Stud length:
with the wheel off, measure from the hub face to the tip of a stud. Drawing
Wheel pad depth:
on the new wheel, the distance from its back face (the side that touches the hub) to where the lug nut's seat starts in the lug hole. Some wheel makers list it (how to measure it). Thick-padded aftermarket wheels often eat 5–10 mm more stud than factory ones.
Thread engagement:
stud length minus spacer minus pad depth is how much thread the nut can grab. It should be at least one stud diameter (12 mm on M12, 14 mm on M14). Below that the nut can strip or pull off.
Slip-on vs bolt-on:
slip-on spacers sit on the factory studs, so they use up stud length. Bolt-on (adapter) spacers, usually 15 mm and up, bolt to the hub with their own nuts and give the wheel new studs. The factory studs must not stick out past a bolt-on spacer's face, or they push against the back of the wheel.

Size comparison

Baseline
New
    Speedometer
    Gearing