Big Tyres VS Fuel Economy

[South]

Hey Guys and Girls,

Im looking at fitting up some 33" tyres to the NJ 3.5L, but was wanting to hear peoples experience with fuel economy. Basically the car is a tourer more than a rock hopper, so I dont want to kill the economy whilst on long stretches of road (doing the kimberlys next year). Presently we get 1000km to a tank (150L) running on tiny 30" tyres and I would like it to stay as close to that as possible.

Does anyone have this combination? Has economy improved or suffered? At present it revs around 3200rpm at 110km/hr, what would it drop to with 33s?

I appreciate your replies...
South

[STIKA]

I have a 60 series and i run 32 and 35
By going to the 35 it zaps power from the motor and i get between 50- 80 km less per tank of fuel. The Km readings are taken form GPS so trye size does not come into affect. The engine RPM droped by 250 RPM

I hope this helps you

[TuffRR]

If its mainly a tourer, what benefit will going to 33's provide?

[Grantw]

If you want to keep everything the same, you may change diff ratios to match the 33's. I think you may have 4.6's so some 4.88's will bring the 33's back to standard.

[South]

33s with give that extra diff clearance we need whilst traversing the Kimberly region next year. Some of the side tracks are going to be slow terrain, driving through water crossings, lots of ruts etc etc. The last trip we did in the wet I got hung up on the diff going through a muddy section. Had to drive in the ruts, there was no other way around. Could have given it more gas before I drove through, but I dont want to smack the diff on every obstacle we come across.

Maybe tourer was a bit soft a definition. We drive lots of tracks, but we dont do the extreme stuff.

Another reason for the 33s is that 31s look too small with a lifted Paj, and I cant find BFG or Cooper 32x10.5x15. Have the standard GLS 15x7" rims, so cant go to an 11.5" or 12.5" width tyre.

[awbeattie381]

ive seen many vehicles with 7 inch rims running 33s.

[South]

But what width were they?

[Grantw]

Go for some 33x10.50x15 or 255/85/16 BFG Muds... 33" high and only 10" wide... Fit a 7" rim easy.

[South]

Damn iinet, I made a post and it disconnected at the same time :(

Yeh im looking at the 33x10.5x15 BFG ATs...

But my concern is the economy. Does anyone have a 3.5 manual on 33s? If it drops a few hundred rpm then economy will be better, but if it totally drops off the torque curve on hills and the like then its going to be a guzzler. So real world figures would be appreciated.

[4runna]

Sorta posted this in the other post of NJs.

30 HT > 31MT with 2.8TD Man. abt 1.5l /100k diff. revs @ 3100/110kmh (I'm pretty sure)

Rob

[dinos4x4]

i had some bfgs 33x10.5 ats on the standard 15x7 alloys

i think the 7inch rims were to narrow , because when the tyres were at road pressure say 34 psi there looked rounded across the tread

they seemed to wear quickly

i will increase the amount of fuel you will use because the motor has to work harder to maintain cruising speed in5 th gear or fourth in a auto

[dinos4x4]

i had some bfgs 33x10.5 ats on the standard 15x7 alloys

i think the 7inch rims were to narrow , because when the tyres were at road pressure say 34 psi there looked rounded across the tread

they seemed to wear quickly

i will increase the amount of fuel you will use because the motor has to work harder to maintain cruising speed in5 th gear or fourth in a auto

[Grantw]

i am running 255/85/16 bfg muds as roadys. With a 3.5L auto, I get 450km to a tank. (350km if i use the right foot or if the missus drives). 100km/h is about 2400rpm.

[awbeattie381]

But what width were they?

33x10.5