How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.96%

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

-1.96%

Absolute Difference

-0.61"

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
2019.6-0.4
3029.4-0.6
4039.2-0.8
5049-1
6058.8-1.2
7068.6-1.4
8078.4-1.6
Tire 1Dia. 31.07 ″Rim 17 ″7.04 ″Width 10.83 ″Revs/Mile 649.0Circum. 97.6″Tire 2Dia. 30.46 ″Rim 17 ″6.73 ″Width 11.22 ″Revs/Mile 662.0Circum. 95.7″
Tire 1
Specification
Tire 2
31.07"
Diameter
30.46"
10.83"
Width
11.22"
7.04"
Sidewall
6.73"
97.624"
Circum.
95.707"
649
Revs/Mile
662

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