How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

2.42%

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

2.42%

Absolute Difference

0.67"

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
2020.5+0.5
3030.7+0.7
4041+1
5051.2+1.2
6061.5+1.5
7071.7+1.7
8081.9+1.9
Tire 1Dia. 27.63 ″Rim 17 ″5.31 ″Width 8.86 ″Revs/Mile 729.9Circum. 86.8″Tire 2Dia. 28.30 ″Rim 17 ″5.65 ″Width 8.07 ″Revs/Mile 712.7Circum. 88.9″
Tire 1
Specification
Tire 2
27.63"
Diameter
28.3"
8.86"
Width
8.07"
5.31"
Sidewall
5.65"
86.802"
Circum.
88.905"
729.9
Revs/Mile
712.7

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