When should the timing belt on a 2015 BMW 320d with 77,000 miles on the clock have the tensioner checked annually and adjusted?

Do you know what a timing belt or a timing chain is and what they do? Could you find them on your vehicle's engine if you had to? If you answered no, don't sweat it. Both are buried behind a lot of ...

I think the belts are the ones with "teeth" so its very hard for them to slip, it may stretch tho, so if its done about 100/120 km you should replace it. (don't want a timing belt to break on you. To ...