I am going to be taking a trip with four large adults and luggage in my Hybrid premium. This will be around 250 miles each way. I have the 15 inch tyres which are currently as the came from the dealer (36psi). I will probably have about 800 miles on the clock when I start this trip, though I would guess still under 600 miles engine on. Most of this trip will be on Motorways (M1 and M25). Are there any tips or should I just get in and drive?