How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-0.3%

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

-0.3%

Absolute Difference

-0.09"

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
2019.9-0.1
3029.9-0.1
4039.9-0.1
5049.8-0.2
6059.8-0.2
7069.8-0.2
8079.8-0.2
Tire 1Dia. 29.57 ″Rim 18 ″5.79 ″Width 9.65 ″Revs/Mile 681.9Circum. 92.9″Tire 2Dia. 29.48 ″Rim 18 ″5.74 ″Width 10.43 ″Revs/Mile 684.2Circum. 92.6″
Tire 1
Specification
Tire 2
29.57"
Diameter
29.48"
9.65"
Width
10.43"
5.79"
Sidewall
5.74"
92.912"
Circum.
92.603"
681.9
Revs/Mile
684.2

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