How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.42%

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

-1.42%

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
2019.7-0.3
3029.6-0.4
4039.4-0.6
5049.3-0.7
6059.2-0.8
7069-1
8078.9-1.1
Tire 1Dia. 28.95 ″Rim 16 ″6.48 ″Width 9.25 ″Revs/Mile 696.6Circum. 91.0″Tire 2Dia. 28.54 ″Rim 16 ″6.27 ″Width 9.65 ″Revs/Mile 706.7Circum. 89.7″
Tire 1
Specification
Tire 2
28.95"
Diameter
28.54"
9.25"
Width
9.65"
6.48"
Sidewall
6.27"
90.958"
Circum.
89.659"
696.6
Revs/Mile
706.7

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