Benna replied:

in respect to intercoolers.

The reason why people fit bigger intercoolers is to increse pressure in the turbo. So if that is what you want that is the way. Of course bigger pressures can mean more problems. Also why go safari, i dont know the prices but i guess they are heaps more expensive. Speak to performance mechanics, they install hundreds of these things, that need to deal with a lot bigger pressures than Safari would.

Geoff replied:

Piers,
When I fitted 285/75's to my GU 4.2TD a couple of years ago, I found that the effect on acceleration was very minimal, the speedometer read spot-on (was showing 8% fast!), and the odometer measured 4% short.
It had only done 13,000k at the time, but has now done about 55,000k and seems to be just starting to loosen up, so any loss of acceleration from the larger tyres has been well and truly negated. I bought Goodrich All-Terrains, haven't had any probs and are wearing very well.
Cheers,
Geoff

Truckster replied:

Theres another thread or 12 on intercoolers here.

Safari to me are way too expensive for the size they are. You can do LOTS better looking at other manufacturers.

If your in Melbourne, try D&F Racing in Aster Ave Carrum Downs, ask for Andrew. He makes intercoolers for race cars and others, and knows his stuff, also his work with TIG welding is amazing. he is also a Patrol owner!

The tire thing has also been done. You didnt mention if its an Auto or Manual? Both react differently.

If you go up 2in in tire size, you (everyone differs, I noticed a LOT with 2inch increase) may notice a slight difference in acceleration, also you will not have the low down offroad as you did before as your gearing the car for better high speed. Also depends on the type of tire you are going to. MT or AT, again both react differently on the road...

As for the Speedo, if its the same as GQ, Nissan sell the gears to change the speedo back to std. The gear is around ~$15 and easy to change.

HTH.
YMMV.

Slunnie replied:

Hi Piers

I can not comment much on the intercooler, though I have changed tyres from 235/75/16 (29's) to 255/85/16's (33's). The tyre you want is also a 33, and what I do find is that you notice the flex in the sidewalls a lot more than with the smaller sidewalled tyres. This I suspect is why manufacturers moved from 15 to 16" rims and some are now moving again to 17 and 18" rims. This sidewall flex make it less pleasing to drive, and this said I don't think I will be changing back though.

Acceleration in my Discovery I found blunted from a stand still, but after this is ok, but brakes is where I notice it most, though this is something that is easily rectified. If you do go to the 285/75 which I think is more than 15mm larger than the std tyre, you will have to have it engineer approved (in NSW at least) who will check it doesn't rub anything, it still stops well and the instruments read accurately. I think this costs about $150ish.

You may also need to check your new roof height with a tape measure to work out your car park status.

Regards
Slunnie

Bob replied:

I fitted a Safari intercooler to my 4.2 TD GU Patrol.
Power increase very evident but major overheating problems when towing large loads at lower speeds such as long hills.
I think restricted air flow through radiator is the problem.
Safari not interested in the problem first blaming fitter (Safari approved) then engine tune (Since checked, OK), then radiator fan (all OK) then giving up.
Lots of luck.

desert replied:

Seems your style of 4wd driving is the same as me.Therefore I would say that the minimal gain in ground clearance is not worth the down side of going to an un-common tyres size. If you were rock hoping and mountain climbing all the time then it would be a different story.Likewise, if you were unlucky enough to stuff a tyre in that environmentn then it is no big deal to drive home on the spare or pop out to civilisation somewhere and buy another. Not so for long distance outback touring and desert trips where most stores or remote roadhouses would never stock a 285 tyre. Stick with the 265 which is identical (almost) in height with 235/85 and 750x16 and if you are running on 7inch rims and not the factory 8's, then almost any tyre can interchange; thus 235/85 245/75 265/70 270/70 etc,etc and at a pinch a 750x16 will also go onto a 7 inch rim, which would also get you out of the scrub in an emergency. Also consider that the 285's are max. rated as a load range C and so, will not have the sidewall strength to live in true cross-country, hard desert type environment.
Cheers