My E250 Coupe has a slow puncture that may need the tyre replaced. It has Continental 255/35R/18 tyres on it with a rating of 94Y. I have had difficulty getting one of these locally and the usual tyre centres are not confident of getting one soon. I notice online some of the other brands such as Bridgestone had tryes with a rating on 94W. I can get one of these locally today but not sure if it will be ok. The letter is a speed rating and I was wondering if I could mix that with the 94Y I already have on the car. Ideally I would prefer to have the same tyre but cannot wait too long, the spare is a space save job. Has anyone any experience of getting tyres via the main dealers or is that a non-starter. If so, who is the best for Continental tyres in the Central Belt of Scotland?