Fuel consumption with bigger tyres

Hi Ingo

To maintain high accuracy I measure my GU 4800's 16.5lt/100km long term average against the GPS which shows an odometer correction factor is required.

for my 265/75/16 wheel set the oddmeter is correct

for my 235/85/16 wheel set oddometer reads 1% low

for my 255/85/16 Coppers odometer reads 4.0% low (they are almost worn out).

for my 255/85/16 Bighorn near new mud terrain wheel set the odometer is 5% low

Minor corrections also occur when tyres are at low pressure but GPS trip meter corrects for this.

The above is in close agreement with what you would expect.
I.E. the diference between 32/33in tyres is that 33in read about 3% low on odometer
which has no relationship to speedo readings.

P.S Lumpy tyres use a lot more fuel , espically if not at high pressures (40+)

How about a swap.
Go a tank full and swap your old mans patrol wheels and tyres to see if the same thing happens on his vehicle.
You then have a chance to see yourself if its tyres or some other issue.
Shane

Ingo57 - You need a petrol station towed behind your car - That's a lot of fuel :-)

Ingo57

Running 265/70R16 Duellers, then 285/75R16 Duellers, then 285/75R16 MTR's and then 285/75R16 MT MTZ's all on a 03 Patrol 3.0L diesel, I found that bigger tyres once you had corrected for the effect bigger tyres had on the odometer had no effect on fuel consumption. More aggressive tread types did however increase fuel consumption, although most of my driving is on the highway, rather than stop-start driving around town.

Snowy

Have you had your truck on the Dyno? I used to have really high fuel consumption and after a dyno tune they found the MAF sensor was faulty. After a good tune and new sensor I was getting much better fuel consumption. I only have the 4.5 though

It's manual and I get on the highway anything between 630-650 out of 115L I have a roof rack as well. Around town I get around the 550km's