why he wants me to write "with my tyres" if he didn't say " com os meus pneus"?
Well this is not possessive. It's just I had a problem with the tires, not MY tires.
Not any more than in the English word "pneumatic" having to do with air and sharing the same root.
Wheels of cars are made from steel, aluminum etc. The tires are made from rubber. The tire is attached to the wheel. Note that you never say that you have a flat wheel. ;)
wheels = rodas
ENGLISH CORRECTION: Tyres = usually rubber, circular and fit on cars and other similar vehicles. Tires = to grow weary (in English).