the tyres are aftermarket non standard fitment, on 18 inch alloy wheels, i am not sure if they are suitable for towing a caravandon't think it realy matters what size are on your car,the manufacturers take that in to account based on weight/speed rating etc as long as there legal[tread depth etc]are the tyres the original spec?
thanks guy`s, that answers my question perfectly.Low profile tyres generally give better grip and stability because there's less sideways flex in the tyre sidewall. The down side is a harsher ride.
The standard tyre for your car was 195/65 R15 91H. The 235/45 R18 tyres fitted should have Load Index 94, which is fine as it's higher.