new tyres

[littlejim]

Just reshod the Prado with a full set of Cooper LT225s; had run the others down to (?below?) the legal depth.
Now have to drop back a cog on rises I use to get over in top!
Tread depth 137mm.
Think the petrol consumption figures might look good for a while, most of the driving is on the flat.

[rayken1938]

Check your soeedo against a gps sounds like you have radically altered your gearing.and will have to adjust your driving habits and drive by your taco.
Cheers
Ray

[Mupster]

Coopers have deeper tread than factory stock tyres, so overall circumference is different for same size, especially in LT sizes!

[scottar]

Just reshod the Prado with a full set of Cooper LT225s; had run the others down to (?below?) the legal depth.
Now have to drop back a cog on rises I use to get over in top!
Tread depth 137mm.
Think the petrol consumption figures might look good for a while, most of the driving is on the flat.

Don't be surprised if the extra tyre diameter actually increases your consumption. Going up one profile in the Nissan Patrol I had made the speedo accurate (at worst a 5% error prior) but also cut the range from the tank from 1100 km to 1000.

[littlejim]

Followed Ray's advice and put the GPS on for a while.
Looks like where I had a speedo fudge factor of about 5-6K at 100, it is now only a couple of K, and at the lower speeds it is virtually spot on, instead of under-reading a bit.
Have just done a trip to the coast and back, with a petrol top up on the way back, looks like a 1.4MPG (I'm an old fart) improvement on previous trips.
Note Scottar's comments, but the trip to and from the coast is mainly flat with a drop down the escarpment on the way down and a short sharp uphill bit on the way back.
Plus there is now a long 80K* section in the middle which must help consumption figures.
* was 100K before they did the road up????? An earlier bit was 100K when dirt, now 80K after being converted to wide bitumen with radiussed curves????