Park level. Keep the car loaded.
Normal tire pressures, normal ride height, wheels straight. Don’t measure with the suspension hanging. Never crawl beneath an unsupported vehicle.
THE INDEPENDENT FITMENT TOOLSTREET / TRACK / YOUR NEXT BUILD
EVERY MILLIMETER COUNTS.
OWN
YOUR
STANCE.
The right wheels change everything.
Dial in your width, offset and tire size.
Know your fit before you commit.
+THE SWEET SPOT
WHERE FORM MEETS FIT.
WHERE FORM MEETS FIT.
WHEEL SIZER / V.02SCROLL TO THE GARAGE ↓
01 / THE GARAGE
SPEC IT.
THEN SEND IT.
Your next setup starts here.
One journey. Every corner covered.
Four steps to your next setup. 01 / Baseline: tell us what is on the car. 02 / Measure: check the space around it. 03 / Goal: choose your next wheels and tires. 04 / Results: review the calculated fitment before you buy.
ENGINEERING NOTE / 001
MORE WHEEL.
SAME ROLLING DIAMETER.
Upsizing usually trades some tire sidewall for more wheel, keeping the overall diameter close to the original. It won’t meaningfully close the vertical arch gap. Width and offset change how far the wheel and tire sit in or out.
02 / THE FIELD GUIDE
MEASURE TWICE.
BUILD ONCE.
Illustration only · not to scale
Measure out to the fender. A
Hold a straightedge vertically from the fender lip. Measure horizontally from the widest tire sidewall to that line. Account for the inner fender lip and liner, not just the painted outer edge.
Check the inside, too. B
Measure tire-to-suspension and rim-to-suspension clearance separately. Use a professional if access is limited. Have them check full steering lock and suspension travel before approving a setup.
Keep room for real life.
Allow for tire flex, passengers, bumps and alignment. Repeat for both sides and each axle. A flush static look isn’t a guarantee against rubbing.
03 / PADDOCK NOTES
KNOW YOUR SETUP.
Can I look up my factory wheel specs?
This version uses manual entry. A dependable stock database needs year, make, model, trim, market, brake package and axle, plus a licensed data source. Confirm your actual wheels: a previous owner may have changed them.
How do width and offset work together?
Lower ET pushes the wheel outward. Higher ET moves it inward. Adding 1 inch of wheel width adds 12.7 mm on each side at the same offset. Tire sidewall movement is estimated separately from nominal tire width.
How wide should my new wheels be?
Choose a tire width first, then use the exact tire manufacturer’s approved rim-width range. Try widths inside that range here and measure inner clearance. A wider rim alone doesn’t tell us the tire’s final sidewall shape; this calculator does not approve tire-to-rim compatibility.
What must I confirm before ordering?
Vehicle-approved overall diameter tolerance, axle load and speed ratings, tire model’s rim-width range, bolt pattern, center bore, fasteners, brake and spoke clearance, TPMS and alignment. Downsizing can cause brake interference. AWD and staggered setups need the vehicle maker’s front-to-rear circumference requirements.
Further reading: Tire Rack: plus sizing ↗ · How fitment is checked ↗