When I bought my car, it had 3 different makes of tyre, sized 205/60/R15 91V. The rear ones are Enduro Runways (done 30k miles on them and still loads of tread. The front ones (Kumho and Fortuna) now need replacing and I'm not sure what to put on.

I do mainly motorway miles, about 20k miles a year and drive fairly gently. I currently get 60-62mpg on the motorway and about 45-50mpg around town. I sometimes use the car on wet grass with a caravan, and on sandy beaches towing a boat. What do you recommend?