Gearing/Tyres for a 70mph cruise

Lots of people here seem to be able to cruise happily at 70mph. My 90 is on the smaller 205 tyres, and I feel it would be revving a lot at 70. Are most people posting here on 7.50 x 16s - or am I being too cautious?

mines happy at a gps'd 80 when running bp ultimate

SteNova said:

mines happy at a gps'd 80 when running bp ultimate

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What size tyres are you running? - from the photo they look a bit bigger than 205/80 r16s. Moving up to 7.50s will give me close to 10% higher gearing, so the same revs at 66mph rather than 60mph.

Stick a disco transfer box on you will do 70 with ease then.

But you will struggle on every hill

Very true if you've got big tyres on but don't think he has big tyres so should be fine.

danny6801 said:

Very true if you've got big tyres on but don't think he has big tyres so should be fine.

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I'll need new tyres in the coming year anyway, easier than changing the transfer box. Something to think about though. Will the disco transfer box go straight on to the early LT77? I'm planning to buy another complete gearbox and rebuild it over the winter, so it might be worth doing then.

Yes will fit straight on only difference is the ratio on high. When on low is the same as the defender transfer box.

I have 7.50 x 16

I also have the 1.4 ratio transfer box

On a hill you just drop to 4th

Thanks for all the info guys. Definitely going to look for a disco xfer box when I get to doing the gearbox rebuild this coming winter.

Mine is n/a but with 1:6 transfer. Ex military etc. So if I just stopped the transfer to 1.2 disco 200tdi type. Lt177 I think. I will cruise better yes ?

It has 7.50 r16 all terrain Michellin tyres

I have a set of cooper STT 255/70/16 that I took off another motor which have only done 1000 miles. Would the 2.5 NA engine cope with these or should I sell and buy smaller?

For all the people like me with these questions - it's well worth a look at the ashcroft transmissions site. They have a ratio calculator which will show you what revs you are pulling at different speeds, depending on gearbox/transfer box/tyre size.

Of course, I should have given you the link:
Ashcroft Transmissions - Ratio Calculator

I'm Considering swapping my 110 from a 1.67 to 1.4 transfer box, on 7.5 x16's. Has anyone got any feedback who's done similar? I don't want it to end up struggling up every incline but it'd be a big bonus to lower the strain on motorway cruising.

I wouldn't go lower than the 1.4 bid personally I just don't think the NA has the oomph to run the 1.2.

Would be fine in the flat but suck mega on the hills more than it does already.

Andrew I have the 1.4 in mine, come down my way and your welcome to have a drive

Cheers, I'm going to give it a go. My current box leaks a tad so its gonna need new gaskets so I might as well swap it for a 1.4. Not going anywhere near 1.2, as you say I'd never make it up hills.