How it works

TireFlows

Get diameter, speedometer impact, and alternate sizes — free, no signup.

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-0.18%

Safety Rating

Safe

Within the recommended 3% safety margin.

The 3% rule is a common reference — not vehicle-specific advice. How it works

Speedometer Error

-0.18%

Absolute Difference

-0.05"

Speedometer

Assumes Tire 1 is what the speedometer is calibrated for. Shows approximate actual speed if you switch to Tire 2.

Reading (mph)Actual (mph)Difference
20200
3029.9-0.1
4039.9-0.1
5049.9-0.1
6059.9-0.1
7069.9-0.1
8079.9-0.1
Tire 1Dia. 28.57 ″Rim 17 ″5.79 ″Width 9.65 ″Revs/Mile 705.8Circum. 89.8″Tire 2Dia. 28.52 ″Rim 17 ″5.76 ″Width 8.86 ″Revs/Mile 707.3Circum. 89.6″
Tire 1
Specification
Tire 2
28.57"
Diameter
28.52"
9.65"
Width
8.86"
5.79"
Sidewall
5.76"
89.77"
Circum.
89.585"
705.8
Revs/Mile
707.3

How results are calculated

Tire dimensions are calculated from the metric size format (width / aspect ratio / rim diameter). Diameter, circumference, and revolutions per mile are derived mathematically — no fitment or vehicle data is used.

The 3% rule is a general reference for acceptable diameter difference, not a guarantee. Always check your vehicle manual or consult a tire professional.

How it works