How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

2.65%

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

2.65%

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
3030.8+0.8
4041.1+1.1
5051.3+1.3
6061.6+1.6
7071.9+1.9
8082.1+2.1
Tire 1Dia. 25.31 ″Rim 16 ″4.66 ″Width 8.46 ″Revs/Mile 796.8Circum. 79.5″Tire 2Dia. 25.98 ″Rim 16 ″4.99 ″Width 7.68 ″Revs/Mile 776.3Circum. 81.6″
Tire 1
Specification
Tire 2
25.31"
Diameter
25.98"
8.46"
Width
7.68"
4.66"
Sidewall
4.99"
79.517"
Circum.
81.62"
796.8
Revs/Mile
776.3

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