Have to fit 4 new tyres?

westy22

to my 2009 Discovery 3.

My local tyrefitters tell me that they are only allowed to fit a full set of 4 new tyres to my Discovery - I had only wanted to replace the front pair this month.

Something to do with the fronts and rears having to not have too much tread depth difference otherwise will cause expensive problems for the transmission / diff.

Truth or lie, please?

colino

Believe it or not, it makes very good sense to have equal tread on all four corners on 4x4s just to make sure the diffs (or electronics in others) are not constantly fighting each other. It's not for any retailer though to tell you what to do, if the "good" pair aren't too knackered, it put them on the front and the new ones on the back. Your Disco will cope.

Tobster86

I've heard of this and it seems to be true to different degrees for different cars.

The greater the disparity in 'overall' wheel size (i.e. total diameter from edge to edge of the tyre, including tread) the more stress this places on a diff. This is true for two or four wheel drive.

There is some degree of stress tolerance engineered into diffs. There has to be to allow for temporary differences in inflation pressures, the effect of turning (which is chiefly why they were invented), etc.

The question is whether or not the stress is within tolerance, and that depends on the vehicle.

For 4x4's, I'd imagine front-to-rear would be a lot less significant than side-to-side.

Hopefully someone can post some information specific to your vehicle, or you may be able to find out via a Land Rover forum?

westy22

In fairness to them, the tyrefitters did go round and manually measure each tyre tread depth and then consulted some figures on the computer before saying that I had to have all 4 replaced together. They must have found that the difference between new tyres and the old pair would be too great and outside recommendations.

All 4 tyres are low on tread and need replacing - it was purely economics (at the best part of £200 per corner) that was leading me to replace a pair this month and the other pair next month

gilbert_and_sullivan

Does the centre diff overheat if you drive a Landrover on winding roads or off road i wonder, no 'diff'erence in what happens when the diff sorts minor discrepencies in circumference out.

Common sense here as in everything, are the 2 worn ones that are staying for a while down to less than 2mm?, are you having General Grabbers (Defender style) with 12mm of tread put on or something with the standard 8mm whilst your two nearly theres are more like 4mm?

Tobster86

westy22 wrote: »

it was purely economics (at the best part of £200 per corner) that was leading me to replace a pair this month and the other pair next month

I don't mean this in a derogatory manner, but surely those economics were factored into the decision to buy a three year old Discovery?

If the tyre fitters have consulted specified tolerances, and seem honest, I'd definitely take their advice.

Nobody wants to throw away good tyres, but the cost of repairing/replacing diffs? Lets not go there!

westy22

All 4 are still legal (just) - they are Pirelli Scorpion Zeros and I was looking to fit the same again as I have had 26k out of the last set which I was very pleased with.

I do mostly high speed motorway; lots of local A and B roads; a little off-road (but usually fields etc rather than rough ground).

westy22

I don't mean this in a derogatory manner, but surely those economics were factored into the decision to buy a three year old Discovery?

Yes, fair comment. I just don't like using plastic and would have preferred to spend £400 this month and £400 next month. It's not a deal breaker though - if the advice is to get all 4 changed together than I will have to bite the bullet.

Hintza

You should be able to save a little bit on your £400.

But have a look at Cooper Tyres an American tyre that I have started using.

Edit:-

I presume you are in the sorry position of being on 19 inch rims? There doesn't appear to be much choice and there isn't much price wise between the Zero and Cooper 4XS (perhaps £20 cheaper @ £140).

westy22

Yes, Hintza - 19 inch rims. Tyres 255/55/19 XL V111 - I will have a look at Cooper (every little helps!)

daveyjp

Camskill have the Pirellis for £155.20 plus delivery.