Diff ratio, tyre size and fuel consumption

Jaco Versfeld · Post by **Jaco Versfeld** » Mon Oct 27, 2008 11:10 am

Hi There,

If a 4y is fitted with diffs with ratio 5.10, uses 31 X 10.5 R15 tyres, will the fuel consumption be influenced when driving on tar at 120 km/h?

Thanks a lot,
Jaco

Post by **Family_Dog** » Mon Oct 27, 2008 6:15 pm

Probably. I used to only get a shade over 5km/l when I had a Weber carb, get about 7km/l now since the EFI conversion. With the bigger tyres, the sppeedo speed is just about spot on too, according to the GPS. Diff ratio in mine is the standard Import diff, I think 4.875 <?> : 1.

-F_D

ThysdJ · Post by **ThysdJ** » Mon Oct 27, 2008 6:31 pm

Jaco, Bigger tyres have many influences on your vehicle.

It changes the gearing of the vehicle, and on a 4y bigger means less power in the high gears, and you need to gear down more frequently to get up hills and stuff, which will have an impact on fuel consumption.

Rolling resistance is another thing that needs to be taken into account, as there is more rubber in contact with the road surface.

Wider tyres will also produce more wind resistance.

That said, the Hilux is not exactly the most aerodynamic vehicle on the road, and driving it at 120km/h will produce a heap of wind resistance and drag. Slowing down to 110km/h will reduce fuel consumption drastically and will negate the impact of larger tyres on your fuel consumption.

Umvubu · Post by **Umvubu** » Tue Oct 28, 2008 1:53 pm

As ek baie gelukkig is kan ek 120km/h haal teen 'n helse afdraande. My gemiddelde spoed op die groot pad is maar 90-100km/h. 60-80km/h teen 'n opdraande. 4.875 & 31" bande

Hilux 4x4 Forum

Diff ratio, tyre size and fuel consumption

Diff ratio, tyre size and fuel consumption

Re: Diff ratio, tyre size and fuel consumption

Re: Diff ratio, tyre size and fuel consumption

Re: Diff ratio, tyre size and fuel consumption