Outer Limits 4x4 Board

OK, probably has been discussed before, but I am looking for people who have done it!

I run 265/75/R16 at the moment on the GU TD4.2 diesel, looking to go up to 285/75/R16 for the extra clearence on the diff, and if I'm truthfull because it looks better!

Will I lose speed? Torque? will I notice it from the drivers seat!

Let me chaps hey! There must be heaps of dudes who have done this!

JenoNT wrote:
Will I lose speed? Torque? will I notice it from the drivers seat!

in a roundabout fashion, yes, yes.

you wont loose top end speed, but your acceleration will be slower.
your torque will be reduced due to the gearing change.
you will notice it from the drivers seat.


i dont have a patrol anymore, and when i did it was a different engine, but i ran 33's and it went fine. now i have the surf and my 33's are my play tyres and my 31's my roadies, the differance between the 2 is noticeable in stop-start traffic where i have to accelerate a lot, but any other time its fine

i cant really tell when i swap onto my 33's for play in my lux, i dont think you would notice it much on a trol.id be happy to drive on 33's all the time except i tow alot and then im sure it would make more of a difference.

tyre width and tread type will also will also play a part as well!

when i first got my truck it had the standed nissan tyres, i then put on my

spare 33/10.5 equivilent dunlop grantreck shitters with 1/3 tread and

didnt notice much of a difference but then when i got my 33/12.5/r15

silent armour's i noticed the difference!

more width= more drag, as does more tread!

When I went from 33s to 35s I lost 20rwkw on the dyno had to get it re boosted up to gain 160rwkw again was very supprised how much I lost

When I made that change on my lux I found I gained around 10% in speed, (ie, if the speedo says 90 i'm doing 99, it it says 100 i'm doing 110), which was the most noticeable thing. In terms of acceleration I won't compare the hilux to the patrol because it's just apples to oranges.

Thanks blokes I really appreciate it,

Surely there must be a few blokes in 4.2 TD's out there that have done this?

When I changed from 265's to 285's I noticed a differance so I swapped diff ratios from 3.9 to 4.3, Best thing I ever done more responsive & more touque That was a 4.2 GU Waggon.

Just do it.......... You know you want to.

TUFFMQ wrote:When I went from 33s to 35s I lost 20rwkw on the dyno had to get it re boosted up to gain 160rwkw again was very supprised how much I lost

I have 195rwkw with 33s and 165rwkw with 36s i couldnt believe how much power you lose between the 3 inchs either

JenoNT wrote:Thanks blokes I really appreciate it,

Surely there must be a few blokes in 4.2 TD's out there that have done this?

I've posted dyno sheets on here before.. I lost 100Nm torque and 20kw at wheels on my TD42 GU.

deffinitely lose power and torque. you wont notice it on the flat as much as you can hold each gear longer but the next time you go up a big hill or tow something you will notice the loss very quickly

A mate has them on his 4.2TD GU and although he did notice it initially he got used to it and never really worked his truck hard anyway so it wasn't a big deal. I really notice it on my 3.0l TD GU so stuck with 33's. When I got the 4.8 I went 35's and it really didn't matter much at all .

Mate just went through this on his 4.2TD Cruiser ute. Shop put 285's on when he only really wanted 265's. Took it home and it was a gear worse off. Took it back and took them for a spin then got them to put the 265's on he wanted. Took them for a spin again and the difference was huge. Had it dyno'd with both for the sake of the argument and the cost was about 10hp. He had no lift so stuck with the 265's.

the size, the width, the tread pattern all have an effect. Mate reckons he noticed the fuel difference in swapping from the same size HT's to muddies.

Just something to live with, nothing comes for nothing these days.

bogged wrote:

JenoNT wrote:Thanks blokes I really appreciate it,

Surely there must be a few blokes in 4.2 TD's out there that have done this?

I've posted dyno sheets on here before.. I lost 100Nm torque and 20kw at wheels on my TD42 GU.

Thats a big torque loss.
Was that the same dyno? and same day?
any other different factors?

Mike

It was our dyno, Mainline unit, same day, within 1/2 hour of doing runs, tyres and wheels were the only thing change to see how much of a difference.



Andy

bogged wrote:

JenoNT wrote:Thanks blokes I really appreciate it,

Surely there must be a few blokes in 4.2 TD's out there that have done this?

I've posted dyno sheets on here before.. I lost 100Nm torque and 20kw at wheels on my TD42 GU.

What were the tyres?
Much difference in tread pattern or block height between them?

You can guess where I'm going with this. Tread depth, pattern and air pressure are more likely suspects than just diameter.
But it's also showing that you have 20kw less at the road, which is exactly what you feel.

IIRC, 265 Geolanders, and 285 MT/R's so yes, big difference in pattern, depth, flex in the sidewalls etc.

JenoNT wrote:OK, probably has been discussed before, but I am looking for people who have done it!

I run 265/75/R16 at the moment on the GU TD4.2 diesel, looking to go up to 285/75/R16 for the extra clearence on the diff, and if I'm truthfull because it looks better!

Will I lose speed? Torque? will I notice it from the drivers seat!

Let me chaps hey! There must be heaps of dudes who have done this!

You will gain 10mm extra diff clearance, and your diesel will probably not even notice the difference given that 10 mm can be the difference between tyres with full tread and tyres at 10% tread left. The overall size will only be about 30mm larger than stock.

Hardly worth "trading up" if you already have a good amount of tread left on the 265/75R16's as there is insignificant advantages and almost no difference in appearance (you could only really tell with a tape measure in your hands - 3% difference in overall size).