Looking into your boot and with the floor in the raised position, you should see a compartment set into the left-hand wheel well. If you can see an air compressor and a bottle of tyre jollop stashed in there then you have non-runflat tyres. If there is nothing in there then it is highly likely you have runflat tyres fitted. You mention the tyre size as 255. Is this the same on all 4 wheels or just the rears like on the 43 model? I only ask since runflat tyres are often fitted to slightly wide wheels with a different cross-sectional profile which allows for the much stiffer sidewall of a runflat tyre. The Pirelli system is referred to as SSRF meaning Self-Supporting Run Flat so if you don't have an air compressor, tyre jollop and have 255 tyres at all 4 corners then I'd also expect to see SSRF moulded into your tyres somewhere. All conjecture on my part as I have 235R18 Michelin Latitude All-Seasons on Red Ken.