Tire size calculators, wheel fitment tools, pressure converters, and load specs. Industry-standard formulas for drivers, mechanics, and enthusiasts.
29 tools
Look up OE bolt pattern, tire size, offset, and center bore by year, make, and model — then check if an aftermarket wheel and tire setup fits. No VIN.
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Enter a metric or flotation tire size to get overall diameter, section width, sidewall, circumference, and revolutions per mile. Free, instant, no signup.
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Compare two tire sizes side by side: diameter, width, sidewall, ride height, and rev/mile, plus Preferred ±2% or Acceptable ±3% fitment bands — free online.
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Convert metric sizes like 275/60R20 to flotation such as 35x12.50R20 and back. See the exact equivalent and nearest catalog match — free, private, in-browser.
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See how a taller or shorter tire changes indicated speed. Get actual speed, percent error, and a 25–75 mph table from stock vs new size — free, private.
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Convert indicated odometer miles into real distance after a tire diameter change. See actual miles, percent error, and the diameter ratio — free, private.
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Convert tire pressure between PSI, kilopascals, and bar with NIST-accurate factors. Enter any unit and read the other two instantly — free, private, no signup.
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Look up ETRTO load index 0–150 and see capacity in kilograms and pounds per tire, per axle, and for a four-tire set — free, instant, private, no signup.
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Decode load range letters B–N into ply ratings and tell SL apart from XL (reinforced) sidewall marks. Free lookup for LT and passenger tires, no signup.
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Decode a DOT date code (WWYY or WWY) to manufacture week, year, and age. Get inspect-or-replace guidance from NHTSA-style date stamps — free, private.
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Estimate how gauge pressure changes with ambient temperature using Gay-Lussac’s law. °F/°C and PSI/kPa/bar — parked cold-to-hot estimate, free and private.
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Divide a tire set’s price by expected miles to get cost per mile. Optionally compare set A vs set B and see which is cheaper per mile — free, private.
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Convert advertised wheel offset (ET, mm) to measured backspacing (inches) and back, including the industry 1" flange allowance — free, private, in-browser.
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See how changing rim width or offset moves the outer and inner lips: poke toward the fender or tuck toward the suspension, in inches and mm — free, private.
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Look up ETRTO-approved minimum, measuring, and maximum rim widths for a tire section width and aspect ratio. Confirm a size before you mount — free, private.
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Parse lug count and PCD in millimetres or inches (5x114.3 vs 5x4.5"), then compare two patterns for an exact match — free, private, instant, no signup.
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From hub bore and wheel centre bore, see whether a hub-centric ring is needed and which OD/ID to order — or if the wheel will not fit. Free, no signup.
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Keep overall diameter when moving to a larger rim. Get metric size suggestions within ±3% of your current tire, with Preferred ±2% rows — free, private.
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Compare front and rear tire sizes on staggered setups. See axle diameter mismatch, width delta, and AWD caution bands — free, private, instant, no signup.
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Check whether a tire section sits inside the ETRTO rim-width range. Above max is stretch (wider rim); below min is a narrower spec — free, private, no signup.
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Estimate added poke and remaining stud engagement for slip-on or bolt-on spacers. Practice minimum ≈ 1× stud diameter — free, private, instant, in-browser.
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Look up ETRTO speed symbols (H, V, W, Y, and more) for maximum certified speed in km/h and mph. Full ISO 4000-1 table — free, private, instant, in-browser.
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Start from a target overall diameter and rim, then find standard metric sizes within ±1 inch. Reverse of a size-to-diameter lookup — free, private, no signup.
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Match center, edge, cupping, feathering, flat-spot, or diagonal wear to likely cause, severity, and next steps. No photo upload — free, private, in-browser.
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Convert a tread-depth reading between 32nds and millimetres, then see remaining-life percent versus 2/32 legal and 4/32 wet — free, private, no signup.
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Estimate remaining mileage-warranty value from purchase price, warranty miles, and miles driven — plus cost per mile so far. Free, private, no signup.
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Divide ring-gear teeth by pinion teeth to get the axle ratio in x.xx : 1 format. Confirm 3.73 vs 4.10 before you shop gears — free, private, in-browser.
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Estimate engine RPM from road speed, tire diameter or size code, axle ratio, and transmission gear. See cruise RPM before a re-gear — free, no signup.
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Multiply first gear, transfer-case low, and axle ratio for off-road crawl ratio, then see street / moderate / serious / extreme — free, private, no signup.
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