How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.39%

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

1.39%

Absolute Difference

0.41"

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
3030.4+0.4
4040.6+0.6
5050.7+0.7
6060.8+0.8
7071+1
8081.1+1.1
Tire 1Dia. 29.54 ″Rim 17 ″6.27 ″Width 9.65 ″Revs/Mile 682.8Circum. 92.8″Tire 2Dia. 29.95 ″Rim 17 ″6.48 ″Width 9.25 ″Revs/Mile 673.3Circum. 94.1″
Tire 1
Specification
Tire 2
29.54"
Diameter
29.95"
9.65"
Width
9.25"
6.27"
Sidewall
6.48"
92.801"
Circum.
94.099"
682.8
Revs/Mile
673.3

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