Tire Size Calculator

Compare tire sizes, calculate speedometer error, and find plus-size options. The complete tire sizing tool for enthusiasts and professionals.

30+
Vehicles
14
Speed Ratings
50
Load Indices
10
Plus-Size Charts

Original Tire

225/55R17
26.7" diameter

New Tire

235/45R18
26.3" diameter

Comparison Results

Good Match - Within acceptable tolerances
225/55R17235/45R18
Diameter Change
-1.56%
-0.42"
Speedo Error
+1.59%
60 mph = 59.1 actual
Width Change
+10mm
+4.4%
Ground Clearance
-0.21"
Lower
DimensionOriginalNewDifference
Overall Diameter26.7"26.3"-0.42"
Section Width225mm235mm+10mm
Sidewall Height4.87"4.16"-0.71"
Circumference84.0"82.7"-1.31"
Revs/Mile754766+1.6%

Precise Calculations

Accurate diameter, circumference, and speedo calculations

Plus-Size Guide

Find the perfect upgrade for your wheels

Vehicle Database

30+ vehicles with OEM specs

Speed Ratings

Complete speed and load references

What Users Say

"Finally a tire calculator that shows all the dimensions I need. The plus-size guide saved me hours of research."

Mike T.
BMW 3 Series Owner

"Love the speedometer accuracy chart. Now I know exactly what speed I'm actually going with my new tires."

Sarah K.
Jeep Wrangler Enthusiast

"The vehicle database is incredibly helpful. Found OEM specs for my Tacoma and the recommended upgrades."

Chris L.
Toyota Tacoma Owner

Ready to Find Your Perfect Tire Size?

Use our professional tire size calculator to compare sizes, check speedometer accuracy, and find plus-size options for your vehicle.

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