I am thinking about putting some mud terrain tyres on my 90 td (pre tdi) what i want to know is will these make the 90 slower, i'm also considering putting a slightly larger tyre on some 235 85 or a similar size, i am currently running on 235 70, will the extra height of the trye make the 90 even more slower, if so i will just stick with my all terrains or i could save up and have a spare set of rims with muds on, what do you think?