Tires for the corresponding vehicle must be selected so that their maximum permissible speed is greater than the maximum («design dependent») vehicle speed.
If in a particular case we are talking about a car that has a national operating permit, then the maximum speed of the car is calculated as follows.
Formula for vehicles with Vmax up to 150 km/h.
Vmax = 1.03 V + 3.5 km/h.
Example: specified maximum speed V = 145 km/h.
Vmax = 1.03 145 km/h + 3.5 km/h = 152.85 km/h.
In this case, you must use a bus with an index «Q» or with a higher speed index.
Formula for cars with Vmax from 151 km/h.
Vmax = 1.01 V + 6.5 km/h.
Example: indicated maximum speed V = 163 km/h
Vmax = 1.01 163 km/h + 6.5 km/h = 171.13 km/h.
In this case, you must use a bus with an index «S» or with a higher speed index.
Vehicles with EU type approval.
In the case of a vehicle with EU type approval, the maximum speed is calculated for all vehicles using a formula.
Vmax = 1,05·V.
Example: indicated maximum speed V = 172 km/h.
Vmax = 1.05 172 km/h = 180.60 km/h.
In this case, you must use a bus with an index «T» or with a higher speed index.
The use of tires with a higher speed index is allowed. The same applies to tires with a higher load index.
Note: Instead of a letter «v» you should substitute the maximum speed indicated in the vehicle passport in column 6. This conversion is necessary because all cars, for technical reasons, develop different maximum speeds within the legal tolerance.
Explanation of tire size
Tire | Speed, km/h | 1* | 2* | 3* | 4* | 5* | 6* | 7* |
Summer tires | up to 240 | 195 | 65 | R | 15 | 91 | V | - |
Winter tires | up to 160 | 195 | 65 | R | 15 | 91 | ABOUT | M + S |
Winter tires | up to 190 | 195 | 65 | R | 15 | 91 | T | M + S |
high speed tires | over 240 | 225 | 50 | ZR | 16 | 91 | — | - |
- 1* - Tire width
- 2* - Cross section ratio in %
- 3* - Tire design code «R» (means radial tire)
- 4* - Disc diameter designation
- 5* - Load index/Loadindex (LI)
- 6* - Letter designation of speed index
- 7* - Winter tire/designation also for all season tires
Speed Index Letters / Maximum Permissible Speed
Letter designation of speed index | Maximum speed, km/h |
L | 120 |
M | 130 |
N | 140 |
R | 150 |
Q | 160 |
R | 170 |
S | 180 |
T | 190 |
And | 200 |
n | 210 |
V | 240 |
ZR | over 240 |
W | 270 |
Y | 300 |
- Load index/Loadindex (LI)
- The load index is printed on the sidewall of the tire. It indicates the maximum allowable load that the tire can withstand.
- The load index is indicated in the designation of the tire size, for example, 195/ 65 R 15 91T. It is indicated on the bus according to the ETRTO standard in the form of a digital code. The following table shows the load indexes used by VW with the corresponding tire loads.
Tire load index
Load index | Maximum tire load, kg |
75 | 387 |
78 | 425 |
79 | 437 |
80 | 450 |
81 | 462 |
82 | 475 |
83 | 487 |
84 | 500 |
85 | 515 |
86 | 530 |
87 | 545 |
88 | 560 |
89 | 580 |
90 | 600 |
91 | 615 |
92 | 630 |
93 | 650 |
94 | 670 |
95 | 690 |
96 | 710 |
97 | 730 |
98 | 750 |
99 | 775 |
100 | 800 |
101 | 825 |
102 | 850 |
103 | 875 |
104 | 900 |
110 | 1060 |
112 | 1120 |
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