Am I right in thinking that larger diameter wheels mean more miles to the gallon.
One revolution of a 19in wheel moves the vehicle over a greater distance than say a 17in wheel.
I know there are probably some deep space physics regarding the power required to turn the larger wheel but I was just wondering? Tattoos - Why would you choose to look like the wall of a public toilet?

No.

The overall circumference when the tyre is fitted is the same.

No.

I have done 22000 miles. 13000 with standard GS 17 inch wheels on average 36 mpg in winter and 9000 miles on 19 inch wheels in summer on average 33 mpg. Air con on all year round so no difference with power consumption.

...and Yes the ride is firmer on 19 inch with better cornering but the 17 inch give an overall better ride.

I like them both but they do different jobs. A Land Rover owner since 1988

From a 1974 series III to a 12MY XS FL2 with help of a 1995 D1, 1996 D1, 2005 D3, 2007 D3 and a 2009 FL2.

Theoretically a larger diameter wheel would give you more mpg - like selecting a higher gear. However, if you are reducing the tyre profile height to compensate for the larger diameter, the only thing you will change is ride quality - the larger the diameter gets, the worse the ride quality gets...... fashion hurts sometimes doesn't it  Cheers,
Raz
FL1 TD4 GS Auto 2001 Silver
FL2 TD4 Auto 2007 Black
FL2 XS SD4 Auto 2012 Fuji White

RazMan wrote:

Theoretically a larger diameter wheel would give you more mpg - like selecting a higher gear.

Larger tyres trick the car computer into thinking it hasn't gone as far as it has. The wheel does less revolutions to go the same distance and the car computer gets its distance from the number of revolutions. Therefore, mpg will go down on the computer but will really be about the same in actuality. The diameter of the wheels has little bearing because as stated above, the circumference of the tyre is about the same on standard 17's and 19's. The extra wheel size is compensated by less rubber by approximately the same amount. If you replace the standard 235/65/17 with 245/65/17 then the tyre diameter increases by about 15mm. The speedo starts to read about 3% slower and fuel economy according to the trip computer will increase by about 3% but its not real. What is real is you start to run out of puff going up hills because it affects gearing the larger the tyre diameter.

Last edited by mikehzz on 19th Mar 2012 1:29 pm. Edited 1 time in total

There are other effects. You wear brakes out quicker and risk damage to diffs and axles due to the higher torque pressure of the bigger diameter. There is a benefit where you get more warranty because the odometer is reading lower. I have checked this on mine with 245/65/17 tyres measured against the 5km odometer check areas of our motorways. My odometer reads short by over 3% at around 4.8km.

You could find that your warranty is invalid because of the non-standard wheel/tyre combination. garioch43

2009 Freelander 2 TD4 HSE - Santorini Black/Black Leather
2002 MGF 1.8i - British Racing Green/Cream Leather with loads of walnut and chrome bits

If you put tractor tyres on then it would.

Mines got 19's on and been out in td4s with auto and 16 inch wheels and mine is the worst out of the two on fuel 

Click image to enlarge

What size tyres are on yours and what size are on theirs? You can do a comparison of the diameters and circumference pretty easily online. From memory, the overall size of 19's is 5-7mm larger than 17's with standard tyres, probably more for 16's. Therefore your speedo will be reading slightly slower than theirs. It also comes down to how much air is in the tyres.

This might help....
http://www.etyres.co.uk/tyre-size-calculator.htm Cheers,
Raz
FL1 TD4 GS Auto 2001 Silver
FL2 TD4 Auto 2007 Black
FL2 XS SD4 Auto 2012 Fuji White

MPG is also dependent on tyre type (not size as earlier mentioned). Using winter tyres for example will result in less MPG than summer tyres in the same driving conditions. 2007 Freelander 2 HSE TD4 Manual with Premium Pack & Moonroof.
Stornoway Grey with Ebony Black Pleather, Clear Indicators, Body Side Mouldings etc.

AndyC wrote:

MPG is also dependent on tyre type (not size as earlier mentioned). Using winter tyres for example will result in less MPG than summer tyres in the same driving conditions.

Not in the snow it won't

Gecko,

Good to see you back on here , trust all is well  ______________________
2011 Full Fat RR 4.4 TDV8
2012 FL2 SD4 Auto HSE
2013 Kawasaki Versys 650