I got flat tyre on my 280 for the first time yesterday, and the spare is looking somewhat dubious. When inflated, the tread bulges out towards the middle instead of remaining flat, meaning only an inch or so of it makes contact with the road. Is this normal/is it safe for me to drive around on until I get a new set of tyres?

 

Yup.

 

Awesome, that's good to hear.