thoughts on mpg

[andycook]

people talk a lot on here about mpg of their truck,
one thing ive not seen mentioned is discussion of the tyre size, width and tread type, and what impact this has on the mpg
I would have thought that a truck with 265/70 r16 tyre - maybe a BFgoodrich all-terrain T/A or similar 'aggressive' tread would guzzle more than a truck
with say a narrower 215/70 r16 tyre with a more on-road style tread e.g. a dueller

by analogy, it takes a lot more effort to ride my mountain bike on the road when shod with chunky tyres, than it does with semi-slicks etc

anyone noticed differences with changing tread and tyre width?

[computingfuture]

i calculated mine at about 25mpg thats with new chunky tires.

[Linda]

people talk a lot on here about mpg of their truck,
one thing ive not seen mentioned is discussion of the tyre size, width and tread type, and what impact this has on the mpg
I would have thought that a truck with 265/70 r16 tyre - maybe a BFgoodrich all-terrain T/A or similar 'aggressive' tread would guzzle more than a truck
with say a narrower 215/70 r16 tyre with a more on-road style tread e.g. a dueller

by analogy, it takes a lot more effort to ride my mountain bike on the road when shod with chunky tyres, than it does with semi-slicks etc

anyone noticed differences with changing tread and tyre width?

Nope - when we got the grey truck it had 215 road tyres on - we changed them to 31" MT's and saw not noticeable difference in MPG.

[Sewerat]

Since 1st Sept until 4th Oct ( this year )

On rural / urban / dual carriage ways & motorways we travelled 3186 miles on Bridgestone 265-70-R15's
At a average fuel consumption of 23.56 mpg.

Have'nt updated since earlier this month but must have put another 1000 miles or so since 4th Oct.

KZN 130 Automatic


BOB GET THAT TIMING BELT CHANGED

[chunkymonkey]

From my school boy science... (so feel free to correct me if I am talking out of my tail pipe...) the power that is actually generated by an engine is used in roughly the following proportion:

1/3 Areodynamic drag
1/3 actually running the engine/aircon etc
1/3 on rolling resistance

The rolling resistance part of it is where the tyre size/tread would come into it. if you assume that smaller/narrow tyres make 10% difference to the rolling resistance (made up number) - that is only a 3% total change in engine power - probably not noticable and easily masked by driving styles/weather conditions/journey time etc.

on a bike the difference is more noticable as the big tyres tend to be at lower pressure so much more energy is lost when you are pedalling away...

[marky]

I just fill her up & smile get around 22-25mpg with these tyres on 31x10.5x15

[andycook]

yeah - I guess its the air pressure that makes the biggest difference,
esp where a bike is concerned, as with knobblys you run them at @45 psi, and semi- or even slicks upto 110psi

I was just thinking back to when, dare i say it, i had a Rav4, and put some different tyres on, with a much more aggressive tread, and noticed i was going about 40 miles less on a tank, but I reckon the tyres had a greater circumference - so thats probably what caused the difference

[TonyN]

The air resistance on the tread blocks of M/T's is more than tyres with smaller blocks, but its not a huge deal. Its only on tyres like my 35" Boggers that becomes a big issue.

Mostly bigger tyres over gear the truck, and you give it more welly to keep up with the acceleration you're used to. Plus any extra width increase the weight of the tyre, making it harder to turn.

Its only really a problem once you go over 31" tyres. As linda said, I could get similar mpg after swapping 215's to 31's on the 2.4, but you could tell it was overgeared as the turbo light comes on earlier in the rev range, proving you need to press the throttle harder to keep it going.

If you can resist the temptation to squeeze the throttle harder, and keep to the same sort of throttle openings, you'll be pulling less rpm for a given speed. So on a long run you can save a little fuel.

But once you go over 31" without regearing, the motor needs more welly to keep speeds up, so you loose mpg.

[Gizmo]

passed caring these days.....just fill her up and go with a grin

[qube3]

i calculated mine at about 25mpg thats with new chunky tires.

what tyre size you running and what lift you got??

[Greebo]

passed caring these days.....just fill her up and go with a grin

Ditto. when it gets down to a 1/4 tank i fill it back up, thats about all the thought i give it. would'nt sell it if it only got 12 mpg so what the hell.

[computingfuture]

what tyre size you running and what lift you got??

4in suspension lift and I have 33x12.5's on 15x12 inch rimms

[surfin]

Espagne pour favor ......

I shall be buying my fuel in Espagne in eight days time at 38p per litre so I dont care about my tyres anyway - he! he!