Thread: Serious desert trip with a D1 300Tdi...asking for trouble or AWESOME??

I second that. Taller tyres on the longer trips will likely need either lower diff ratios, transfer case ratios (you can go from the 1.222 in a disco to 1.4 in defender pretty easy) or extra power. My 300tdi manual had diesel gas. You really knew when it ran out of gas!

Originally Posted by Disco-tastic

I second that. Taller tyres on the longer trips will likely need either lower diff ratios, transfer case ratios (you can go from the 1.222 in a disco to 1.4 in defender pretty easy) or extra power. My 300tdi manual had diesel gas. You really knew when it ran out of gas!

Hey mine has the diesel gas too, it's a nice little extra kick even though it only lasts around 700km and I don't know how available gas is out in the desert stops.

Originally Posted by Spel1

Further to this. I did a lot of driving on 235/85-16 on a mostly standard 300tdi Auto Disco, just some cuts and 2" suspension. In an off-road situation, they are great - the low range with those tyres has plenty of grunt, and the ground clearance good too, good in the sand with deflation. But getting to those faraway places in this country might mean driving a long way to get the desert roads. Where I found they were a hindrance was on looong hills and in severe headwinds, just couldn't stay in a useable powerband in top gear without pulling huge egt's. Sure I could drive (and had to) at slower speeds in 3rd, but man that's tedious with a long way to go. Just dropping down to the 31x10.5-15 (245/75-16) equiv has made enough of a difference to make the trips a lot better. Might be different in a manual, but there are less options in a stock auto.

I second this.
I have 31's and a slight susp lift on mine and have had no problems and happy to have the extra underbody clearance. Have done plenty of Vic alps trips as well as the Simpson, Anne Beadell, Cape. Mine is an auto with lock up 3rd which has been good. Look after the car, drive to conditions, it will get you there.

That's very interesting to read. I've also got 235/85 (great tyre generally) but recently when towing our box trailer down to Sundown NP and with all the ups & downs, I too had problems with high EGT's and trying to keep up any sort of speed in my Auto.

I recently only got some new 235/85 tyres but maybe I should try running some 245/75's and see our it goes?

rob

Originally Posted by Spel1

Further to this. I did a lot of driving on 235/85-16 on a mostly standard 300tdi Auto Disco, just some cuts and 2" suspension. In an off-road situation, they are great - the low range with those tyres has plenty of grunt, and the ground clearance good too, good in the sand with deflation. But getting to those faraway places in this country might mean driving a long way to get the desert roads. Where I found they were a hindrance was on looong hills and in severe headwinds, just couldn't stay in a useable powerband in top gear without pulling huge egt's. Sure I could drive (and had to) at slower speeds in 3rd, but man that's tedious with a long way to go. Just dropping down to the 31x10.5-15 (245/75-16) equiv has made enough of a difference to make the trips a lot better. Might be different in a manual, but there are less options in a stock auto.

Originally Posted by edddo

I second this.
I have 31's and a slight susp lift on mine and have had no problems and happy to have the extra underbody clearance. Have done plenty of Vic alps trips as well as the Simpson, Anne Beadell, Cape. Mine is an auto with lock up 3rd which has been good. Look after the car, drive to conditions, it will get you there.

If you try some 245/75s I suspect you will notice a significant improvement in general drivability.
The 235/85s are just to big for a standard (or pump tweaked) 300tdi disco 1 with standard gearing - both on and off rd imo.

Originally Posted by edddo

If you try some 245/75s I suspect you will notice a significant improvement in general drivability.
The 235/85s are just to big for a standard (or pump tweaked) 300tdi disco 1 with standard gearing - both on and off rd imo.

Agree with that. Our D1 had a 50mm lift, but standard 235/70/16s and the auto and it was fine.

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Originally Posted by edddo

....
The 235/85s are just to big for a standard (or pump tweaked) 300tdi disco 1 with standard gearing - both on and off rd imo.

I'd agree.
I wouldn't use 235/85's without first lowering low ratio gears.
With std tyres I reckon it's a bit too high for secure steep descents, add the larger 235's with that aspect ratio and you've raised it again.

something like a VNT would probably address the on road drivability, but does nothing about overall low ratio work.

Does anyone have the difference in gearbox ratios & engine tune / outputs handy?
Between:
Disco 300tdi with 245/75R16's & Defender 300tdi with 235/85R16's

Dors anyone run 245/75's on Defender?