How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.61%

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

1.61%

Absolute Difference

0.46"

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
2020.3+0.3
3030.5+0.5
4040.6+0.6
5050.8+0.8
6061+1
7071.1+1.1
8081.3+1.3
Tire 1Dia. 28.57 ″Rim 17 ″5.79 ″Width 9.65 ″Revs/Mile 705.8Circum. 89.8″Tire 2Dia. 29.03 ″Rim 17 ″6.01 ″Width 9.25 ″Revs/Mile 694.8Circum. 91.2″
Tire 1
Specification
Tire 2
28.57"
Diameter
29.03"
9.65"
Width
9.25"
5.79"
Sidewall
6.01"
89.77"
Circum.
91.193"
705.8
Revs/Mile
694.8

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