Original size
Reads as 205/55R16
New size
Reads as 225/45R17
| Metric | Original | New | Change |
|---|
How to use this
Plus-sizing — fitting a larger wheel with a lower-profile tire — is fine as long as the overall diameter stays within about ±3% of the original. That keeps your speedometer, odometer, ABS and stability-control calibrations honest, and keeps the rolling radius close enough that AWD systems do not fight themselves. This tool colour-codes the verdict: green inside ±3%, amber to ±5%, red beyond.
What each number means for you
- Overall diameter drives your speedometer and gearing. A bigger diameter makes the speedometer read slow (you are going faster than it says).
- Revolutions per mile is what the ABS and odometer actually count. A big change confuses both.
- Section width needs clearance — check the strut, fender liner and suspension at full lock and full compression.
- Sidewall height is comfort and pothole protection. Lower profile looks sharper and rides harder.
Why the speedometer error matters
Your speedometer does not measure your speed directly. It counts wheel rotations and multiplies by a rolling circumference the manufacturer programmed in for the original tire. Change the diameter and every reading is off by the same percentage. Fit tires 3% larger and an indicated 70 mph is really about 72 mph — which matters for both speeding tickets and the odometer reading that determines your car's resale value and service intervals. For the full breakdown of what each sidewall number means, see how to read a tire sidewall.