The following table shows the number of trucks of 6 different brands sold from a showroom during a given period of time.
| Brand | Trucks |
| B1 | 45 |
| B2 | 35 |
| B3 | 36 |
| B4 | 44 |
| B5 | 28 |
| B6 | 22 |
There are 8 tyres on each truck, irrespective of the brand of the truck. What is the average number of tyres per brand?