Want to fit different size tyres front and rear.

[DiscoDancer]

I am driving around Europe and the middle east in my Discovery (mk1) and I've had BFG AT 235/70/16 tyres on. These have been brilliant for the first 30k miles. However shortly after this I experienced first a (repairable) puncture, then an injured sidewall resulting in a huge bulge and finally another puncture resulting in a cooked tyre - these problems appearing in the tyres fitted to the rear axle, which had about 1/3 of the original tread left. I am so impressed with the BFGs though - I've put them through all kinds of hell, speed on terrible roads, sharp rocks and they came through (albeit with fairly pulverised tread patterns and a number of minor sidewall slashes) (the brackets holding the body to the chassis are cracking, but the tyres survived...).

So - I want to replace these tyres with more of the same. The front tyres are still good (I have been rotating the tyres during this period, but right now I have two good tyres on the front with about 50% tread left). I think the rear tyres have taken the worst beating because of the weight - I have about 1800kg on the rear axle, which is both about the load limit for the axle and the limit for the tyres (load range C). So I'm trying to decide if I should put load range D tyres on instead. These are a slightly different size (245/70/16) which gives 705 rather than 715 revolutions per mile, so 1.5% different approx. So to the questions:

- is a D range tyre going to last longer - did I start seeing problems with my C range rear tyres because they were close to the weight limit and I was pushing them hard?

- anyone know how the construction of the D range tyre differs?

- and most importantly - I am going to experience problems - either by having a mix of C and D range or by having a mix of sizes front and rear. I suppose as the front are part worn already, they are actually smaller than spec and so this could exacerbate any size-related problems. I realise I will get wind-up quicker in 4x4 mode, but would it have any effects when the centre diff is unlocked?

[BogMonster]

The 235/70R16 AT is load range 104 which is 900kg or 1800kg per axle so you are on the limit but ok.

I would not mix sizes as the centre diff will be turning all the time while driving which is not designed to do. You can get away with it for a while (odd size spare for example) but I wouldn't plan on it.

[axlechorus]

Personnally I would try to avoid having a split range of tyres for both the centre diff and also for spares purposes as you would ideally need a spare for both the front and the rear.

If you upgrade to 245/70 and get a greater load then I would consider it, I know that Kumho do the KL71 in that size which I know someone who had them on a D2 and spoke very highly off them however they where a much softer compound with quiet soft side walls compared to the BF AT.

Alternatively you could consider a change to 235/85 R16 rubber if that has a higher loading either in MT or AT?

Cheers

Ryck