How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.86%

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

-1.86%

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
4039.3-0.7
5049.1-0.9
6058.9-1.1
7068.7-1.3
8078.5-1.5
Tire 1Dia. 32.71 ″Rim 17 ″7.85 ″Width 11.22 ″Revs/Mile 616.6Circum. 102.8″Tire 2Dia. 32.10 ″Rim 17 ″7.55 ″Width 11.61 ″Revs/Mile 628.3Circum. 100.8″
Tire 1
Specification
Tire 2
32.71"
Diameter
32.1"
11.22"
Width
11.61"
7.85"
Sidewall
7.55"
102.757"
Circum.
100.84"
616.6
Revs/Mile
628.3

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