Guide
How much bigger tire you can fit
The 3 percent rule, and what changes as you approach it.
Short answer
Keep the new tire within about 3 percent of the stock tire's overall diameter. At 3 percent larger, the speedometer reads 65 mph when you are doing 67.0, which is about the limit before gearing, ABS and stability control start to notice. Clearance is the other limit: check that the tire clears at full steering lock and full suspension compression.
Plus sizes for common stock tires
A plus size keeps the diameter while the wheel or the width grows. These are the closest options for four common stock sizes:
| Stock | Height | Options |
|---|---|---|
| 205/55R16 | 24.9 in | 225/50R16 (−0.1%), 235/50R16 (+1.5%), 215/50R16 (−1.7%) |
| 225/45R17 | 25.0 in | 255/40R17 (+0.2%), 245/40R17 (−1.0%), 255/35R18 (+0.2%) |
| 225/65R17 | 28.5 in | 245/60R17 (+0.2%), 235/60R17 (−1.4%), 255/55R17 (−1.7%) |
| 265/70R17 | 31.6 in | 285/65R17 (−0.1%), 295/65R17 (+1.6%), 275/65R17 (−1.7%) |
What changes as the tire gets bigger
- Speedometer and odometer read low by the same percentage. A 2 percent larger tire at an indicated 65 mph is really 66.3 mph, and adds 2 miles to every 100 the odometer shows.
- Gearing gets taller, so acceleration drops a little and the engine works harder on hills and when towing.
- ABS and stability control compare wheel speeds and are calibrated for the stock size; a large change can trigger warnings or change how they intervene. All four tires must match on all-wheel drive.
- Clearance: the tire grows by half the diameter change at the top and front, and a wider tire reaches further in and out. Turn to full lock both ways and check the inner fender liner and the strut.
Wider or taller?
A wider tire on the same wheel with the same aspect ratio is also taller, because the sidewall is a percentage of the width: going from 225/65R17 to 235/65R17 adds 1.8 percent of diameter as well as 10 mm of width. A higher aspect ratio at the same width only adds height: 265/75R17 is 3.3 percent taller than 265/70R17.