Tyre Pressures for staggered setup 20"

[NehalX5]

Hi guys,

Was wondering what tyre pressures are best for the staggered setup on M-Sport X5's with the 20" wheels? (275/40/R20 on the front and 315/35/R20 on the rear).
People are stating that they are good at 40psi, which we have always done, but others are saying to stick exactly to the tyre label. Have always run 40 on all the cars, is this so for the X5 or is it very sensitive? Getting a lot of inner tyre wear on the rear as well.

[sapphireblack]

I think i read here only recently that 32psi was working well for that contributor. I'm new to Xs with RFTs so abide by the B post advisory.

I have great experience with the original E53 and regular tyres, no matter what pressures i tried over many years with that, centre wear on the rears was always an issue.

Right or wrong, i stick to what the car maker states. In theory they know their product better than me

A four wheel alignment check is probably worth every penny, especially if new rubber is on or going on soon.

[NehalX5]

That is the problem however. We get tracking every few months due to a scheme the local tyre place runs for tracking. It is always getting done, matter of fact they had to change some tie rod ends because of their tracking discovering that they were seized. Despite getting tracking however, the rears are always getting that same inner tyre wear, and rarely wear across the centres. Our last set of rears had 7mm left in tread but went down to the cords in the centre. Maybe we have been running the wrong pressures, that could be all.

[sapphireblack]

Centre wear is an indication of over inflation i believe, equal edge wear therefore under inflation. Thats what I've always believed but only since I've owned BMWs with fat rear tyres.

Anything uneven, inside or outside edges, is always attributed to tracking afaik.

I know it always comes at a cost but main dealers are sometimes the best options for irritating issues like this, or at least perhaps try a different alignment establishment?

[NehalX5]

Centre wear is an indication of over inflation i believe, equal edge wear therefore under inflation. Thats what I've always believed but only since I've owned BMWs with fat rear tyres.

Anything uneven, inside or outside edges, is always attributed to tracking afaik.

I know it always comes at a cost but main dealers are sometimes the best options for irritating issues like this, or at least perhaps try a different alignment establishment?

Think I will, thanks for the help.

[Leslie]

Remember too the people say use the lower manufacturers pressures are on rigid runflat tyres with very stiff sidewalls , If you are getting severe inside edgewear then a few more psi may be a good idea and see how you go . If you are running ordinary non runflat tyres the manufacturers lower pressures may too a little low to compensate for the more flexible sidewalls . If you are not happy with the wear make a change to the upper pressures which are 35 front /39 rear

[Huxley06]

39psi all round on that setup.

[Huxley06]

And if your still getting inner tyre wear at 40 then go up a couple of psi.....What’s to say your gauge is 100% ?

[Graeme]

The car's set-up leads to wear on the inner edges of the rear tyres, but there are two points to watch. First, increasing the pressure on a lightly loaded car will also cause excessive wear on the centre of the rears, especially if covering long motorway miles - that's when most of the driving force is on the rear wheels. Second, if the wear on the inner edges seems excessive, have the tracking adjusted front and rear. You'll need to go to a specialist centre where they have the kit to set-up the rear tracking as well as the front and line front and rear up so the car doesn't crab on the road.
My advice on pressures is to follow the manufacturer's guidance irrespective of having run-flats or non-run-flat tyres fitted.
Graeme