How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

0.65%

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

0.65%

Absolute Difference

0.18"

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
2020.1+0.1
3030.2+0.2
4040.3+0.3
5050.3+0.3
6060.4+0.4
7070.5+0.5
8080.5+0.5
Tire 1Dia. 27.85 ″Rim 16 ″5.93 ″Width 8.46 ″Revs/Mile 724.2Circum. 87.5″Tire 2Dia. 28.03 ″Rim 16 ″6.01 ″Width 9.25 ″Revs/Mile 719.6Circum. 88.1″
Tire 1
Specification
Tire 2
27.85"
Diameter
28.03"
8.46"
Width
9.25"
5.93"
Sidewall
6.01"
87.495"
Circum.
88.051"
724.2
Revs/Mile
719.6

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