265/75R16

[Tyke]

Right guys.

If we fit 265/75R16's to a 300TDi what will it do the gearing and fuel consumption?

All other things like lift, arch cutting, steering/bump stops etc are not an issue. We are well aware of what needs doing to make them fit and work properly.

It's the effect it has on the motor and how it pulls on the road, compared to 235/70's that I would like advice on.

Does a lot of road miles does my truck and I don't want to totaly destroy the road tractability.

Thinking of fitting decent MT's in 265/75 on the steels and keeping the AT's on the alloys for touring. Could put up with changing them over for localish off road jaunts if that's what it takes, but I'm often doing 400+mile round trips on mixed roads to get to where I'm going.

No room for carrying the spare set of wheels on trips like that as there is often luggage and passengers to consider.

Oh! I don't do much towing, odd recovery, but do carry a bit of a load at times.

Cheers guys.

[Budgie]

Basicly you're going from a 29" dia tyre to a 32" dia tyre so you'll have about a 10% reduction in the number of revs per mile that the tyre does.

The effects of this will be that the mpg when cruising will be better but you may notice that you'll have to give it more revs to pull away, it may struggle to do 30mph in 4th gear & you'll have to use 3rd and your speedo will be reading anything upto 10mph out.

I've got 33x12.5x15's fitted and ended up changing the transfer box for a 1.44:1 ratio box from a TD5 Defender to bring the gearing back to normal, or there's the a 4.11 ratio diffs that will do the same thing and keep the low ratio standard as well, the transfer box change will only effect the high ratio gearing.  

If you're getting good quality mud tyres, like BFG, General, Goodyear etc then they will cope with the distances you talking about and they'll have good road manners and also very little road noise.  

[seph234]

i have the bf goodrich mt's on silver modulars 265/75/16 and yes it kills 5th gear any hill and you will be changing back to 4th so yes it does knock the miles per gallon down too coz you have to drive it a little harder. the tyres are very good on the road and off road they are a lot better than my old tyres(pirelli scorpion mt's).   joe

[PUX]

same as i have bfg mt 265/75/16 and they run fine but u have to drive it a bit harder and the mpg does suffer a bit  :D

[Tyke]

That confiirms what I suspected. Can live with what you guys are saying for local runs but probably keep the 235AT's on the spare wheels for the longer road runs when the muds are not needed.

Looking like it might be a swap for the transfer box sometime in the future.

Will get the tyres on first and see for myself - then take it from there.

Thanks