How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.63%

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

1.63%

Absolute Difference

0.42"

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
2020.3+0.3
3030.5+0.5
4040.7+0.7
5050.8+0.8
6061+1
7071.1+1.1
8081.3+1.3
Tire 1Dia. 25.74 ″Rim 16 ″4.87 ″Width 8.86 ″Revs/Mile 783.4Circum. 80.9″Tire 2Dia. 26.16 ″Rim 16 ″5.08 ″Width 8.46 ″Revs/Mile 771.0Circum. 82.2″
Tire 1
Specification
Tire 2
25.74"
Diameter
26.16"
8.86"
Width
8.46"
4.87"
Sidewall
5.08"
80.877"
Circum.
82.176"
783.4
Revs/Mile
771

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