Thread: Taller Tyres, Shorter Economy?

Combination of several factors.

First - are you using the odometer to calculate mileage? If so, the variation will impact the calculation. You'll need to modify Kilometers travelled by 5% on the larger rubber.

Second - ATs roll better (less resistance) than the blocky tread of an MT, so there will be some additional effort.

Third - Rolling resistance and weight, when in stop start you will notice it even more as the engine works harder to bring the additional mass up to speed.


Hope that helps.

Originally Posted by Bohica

Hello all,
I generally get about 10.25L/100km on the AT's. With the MT's I get 11.1L/100km Is the tyre the difference? The MT's are 245/75R16 and the AT's are 235/70R16. I'm not that fussed about the economy, I bought the car for it's offroad capabilities. I'm just curious.

TIA

Julian

Luckly for you, my old tuned D2 TD5 worst I got was 16ltrs per hundred at half an tank the kms read around 270km

Thanks Tombie, adding 5% gives 10.6L/100k, the added mass etc, I guess adds about 0.4L/100km.
As I said, I'm not that fussed. If I wanted economy I'd have an i30, the i30 can't go where I want to go!!

Wow 16 ltrs per 100k, thats about the same as my late model BT50
John

The other effect worth notinng is that higher tyres increase the effective frontal area of the vehicle - airflow under the vehicle is turbulent on the Discovery anyway, so the added area under the car should be added to the actual frontal area. In fact, it is probably even worse than the calculation this gives, as more air goes there with the increased ground clearance.

Have recently acquired a D2 Td5 auto, running 265 70 16 tyres and it has a 2" lift kit in it, so if added height increases under car turbulance then this car should have that.
Averaged 10.5L to the 100k's and was generally travelling at over 100 and up 125 for most of the trip (2600k's).
So perhaps 10.5 to 11L per 100k's is usual and tyre height makes not a lot of difference to consumption.