How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.71%

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

-1.71%

Absolute Difference

-0.54"

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
2019.7-0.3
3029.5-0.5
4039.3-0.7
5049.1-0.9
6059-1
7068.8-1.2
8078.6-1.4
Tire 1Dia. 31.61 ″Rim 17 ″7.30 ″Width 10.43 ″Revs/Mile 638.1Circum. 99.3″Tire 2Dia. 31.07 ″Rim 17 ″7.04 ″Width 10.83 ″Revs/Mile 649.0Circum. 97.6″
Tire 1
Specification
Tire 2
31.61"
Diameter
31.07"
10.43"
Width
10.83"
7.3"
Sidewall
7.04"
99.294"
Circum.
97.624"
638.1
Revs/Mile
649

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