INTRODUCTION
5
1
1.3.1 Extracting Tire Size From Tire Sidewall Markings
The best way to find out your tire size is to actually look at the tire sidewall. As you can see in
the figure below, there is generally a lot of different information on the tire; however, for our
purpose, we just need 3 pieces of information:
1.
Tire Width
: the “215” designation
states the Width of the tire in
millimeters at the widest point
from sidewall to sidewall when
mounted on the correct wheel.
2.
Tire Height
: the “65” designation
is the Aspect Ratio. This ratio is
calculated by dividing the section
H
eight by the
W
idth. Therefore
the tire height is calculated as:
Height = Ratio * Width / 100
3.
Tire Diameter
: the “15”
designation is the Diameter of the
wheel rim in inches. This is the
exact size that the tire will fit.
Once the whole list of the nominal values of all the tires has been collected, it is very easy to
understand the application needs, and chose the correct STS400™ model. See the following
sample table:
W [mm]
R [%]
D [Inch]
H [mm]
Dint [mm] Dext [mm]
Tire 1
120
70
12
84
304.8
472.8
Tire 2
175
65
14
114
355.6
583.1
Tire 3
185
55
14
102
355.6
559.1
Tire 4
205
60
15
123
381.0
627.0
Tire 5
205
65
15
133
381.0
647.5
Tire 6
190
50
17
95
431.8
621.8
Tire 7
100
100
18
100
457.2
657.2
Tire 8
275
45
18
124
457.2
704.7
Tire 9
275
45
20
124
508.0
755.5
Minimum [mm]
100.0
84.0
Maximum [mm]
275.0
133.3
508.0
755.5
DOF Required [mm]
175.0
Note: Dext is the external tire diameter. Even if this data is not used for the best choice of the
STS400™, the above table shows it. It can be calculated as: Dext = Dint + (2 * H).
