I had on my 300tdi 90 with Disco transfer box until 2 weeks ago 205R16 (the ones that don't have a sidewall ratio). They did the job for me for long enough albeit they are a bit on the small side and make engine revs on the motorway a bit excessive!

I took them off and put on my big off road tyres while I strip the 205R16's off to do the wheels up, as expected, with these fitted the engine sounded much quieter on the motorway but when I was on country lanes I found that I needed to drop gear a lot more, sometimes even into 3rd where I would have normally been able to deck it in 5th and get to the top no bother on the 205's.

I have 2 good Michelin 4x4 235/70R16's left over from the Disco so I was going to buy two more and use that size, the additional width would be good and the tyres are better so grip would be enhanced but I was looking at them all sitting in the workshop and thought they looked awfully similar in diameter, a quick search and I found a very good tyre sizing site which says the 205 and 235 are 734.4mm and 735.4mm diameter, so really, 205's with more tread depth than some 235's could be bigger diameter it's so close!

So I have not made up my mind with regards to tyre size, I was thinking maybe 245/70R16's now which are 250mm in diameter, but I would really like to hear from someone who has a 300tdi on a Disco box and see what tyre gives them a good all rounder, not too small but not so big you lose power.

but you never lose power? you just have to go down a gear or 2?

SteNova said:

but you never lose power? you just have to go down a gear or 2?

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Well I do lose power or else I would make it up the hill, the rev band changes to a point where it falls out the power curve on the bigger tyres and I don't want to shift up and down gears like doing the gearbox shuffle it's just not nice driving.

I am essentially going to fit the smallest tyres I need in the end to suit here. I used to run my Discovery on the 235's over the same roads in 5th all the time, sat back and drove it, plenty power to get up the hills and I wasn't flying through the gears.

265/75 are too tall , so 245/70 should be ok on a ninety as they are a far bit lighter than a disco in normal use , as 235/70 is a normal disco size. To a degree it depends on what your main typoe of use is , lots of motorway then a slightly taller tyre , lots of heavy towing then possibly a less tall tyre . HTSH

Well, probably 50% motorway to be honest, I do tow but I wouldn't imagine anything too heavy and if it was I wouldn't mind driving it slower anyway.

I'll probably get a set of 245's then.

Anyone tried INSA Rangers?

http://www.insaturbo.com/ver/es/ficha/ranger/UmFuZ2Vy

I know I am going to get grilled but I have two sets. One set of insa turbos for off road and one set of road tyres for when I am going on a road trip. Makes a huge difference to acceleration and speed IMO