XSeries-forum

I have just arranged to have two hankooks put on the front of my E53 4.6 as it has been sat for sometime and there is sidewall cracking on the front passenger side.  I was going to get the rears done in probably another couple of months as they are about half worn at present.  The tyres are a mismatch at present, Bridgestone one make on the front and two different types of Bridgestone on the rear.

I have read conflicting information about changing all four tyres and all four being same tread patterns makes etc.
But what is the real truth, the woman at black circles tells me I must change all four and they must be the same, a piece of literature from a car magazine tells me that as long as the axles are the same, the x5 is a "real" 4x4 and therefore this actually doesn't matter as it's more to do with the Volvo and such like that have active 2 wheel drive with assist of 4 when required.

Anyway the hankooks I'm putting on I have just found out do not have a matching model for the rears.
I can get hankooks but different model

Front  hankook ventos rho6
Rear - hankooks ventos evo k107

The law requires that you have similar construction tyres on the same axle.  No mixing radials, cross-ply, RFT/nonRFT etc.

Ideally all 4 should be the same pattern too and there have been issues reported with certain tyres on these cars causing transmission issues, though exactly why has been hard to pin down.  It's a variable 4x4 and can switch between front and rear wheel drive depending upon grip which can upset the system.  Transmission 'wind-up' can result in shattered diffs or transfer boxes.  The outer rolling diameter might actually be the issue and if there is a significant difference (BMW approved tyres have a '*' on them to let owners know that the diameters will match across a set) then you might over stress the system. 

There is no evidence as yet of exactly which tyre types or sizes may trigger this.  Plenty of owners have no issues at all.

The recommendation to change all four at the same time is good advice though not essential.  My E53 wore its tyres evenly so I always changed as a set.  I only ever put Michelin Diamaris on.  My X6 is doing the same and will need a set this year  :'(

Richard

Cheers for your feedback, when It comes to change the rears I will probably have a good sit down and think about the setup, will stick with the hankooks all round this set and then look into going for a matching set next time. 
I've fitted correct sizes to front and the the rears are the correct size, just not same tread pattern at present.

They cannot ultimately be a matching amount of contact and grip for each wheel as the backs are 315 and the fronts 275, this is what initially led me down the path of, what is the actual truth on this matter, but it seems this maybe a doorway to theories and in best practice speeches.

generally talking tread patterns , wont effect the transition unless its one extreme to another (IE off road tyres to dry summer tyres only)

but say for example toyos summer tyre vs bridgestones summer tyre , no , that wont effect it ether

you could ague summer tyres on the front axle and winter tyres on the rear due to the diffrent grip/drag ratios , but again i highly doubt it would cause any damage

what is more important is the rolling circumference this can lead to damage , although in theory thats what the diffs job is but it sadly doesnt work like that lol

Surely when a tyre manufacturer makes a tyre, the size they put on the wall is the total size inclusive of tread. Therefore as long as I fit the manufacturer recommended sizes, bobs your uncle? In theory, I mean

[quote="Jackstrath"]
generally talking tread patterns , wont effect the transition unless its one extreme to another (IE off road tyres to dry summer tyres only)

but say for example toyos summer tyre vs bridgestones summer tyre , no , that wont effect it ether

you could ague summer tyres on the front axle and winter tyres on the rear due to the diffrent grip/drag ratios , but again i highly doubt it would cause any damage

what is more important is the rolling circumference this can lead to damage , although in theory thats what the diffs job is but it sadly doesnt work like that lol
[/quote]
Apparantly you could put different tyres on the same axle, ( tread depth wise ) without a problem, as the diff will sort out the different speeds, due to the circumference .  But when there is a difference in rolling diameter between the front and rear axle, all the strain is taken up by the transfer box, and on the doffs via the prop shaft side.
Hence the wind up problems.

So what your saying is really they need to wear at the same rate, within a degree of tolerance, therefore, brand new on the front and about shot on the back would give the wind up effect, maybe.

in theory lol , im not sure if this is still the case but im sure Michigan come with a extra mm of tread

but on another note , cars arent as sensitive as you would think to tyres , ie if i put brand new track tyres on my race cars front axle and new road tyres on the rear , there is 2mm of tread diffrence , now if this was a massive issue , the abs would fault as there is a difference in wheel speed  , but it doesnt lol

i could be wrong , but we have a center diff inside the transfer box , thus doing the same job , its like old landys ect that dont

Sounds like people are trying to worry me too much and I shall be fine.

People aren't trying to worry you at all.  Just report incidents - some of which are on this forum - that have occurred where it might the tyres causing transmission wind up.  In most cases you won't have any issues at all but being aware of them at least gives you more info to put in the decision process.

BMW aren't the only folks with specific tyres.  Merc, Audi and a few others have the same.  In the BMW case the rolling diameters are modified to match on the staggered setup..

The xDrive system (inside the transfer box unit) is a variable ratio drive system with a chain drive for the front prop shaft and a wet multi-plate clutch to shift torque as necessary.  The front and rear diffs are open type and use the DSC/ABS to control grip in the event of slipping by braking the slipping wheel.

Richard

X5sport, I was mainly on about the woman from black circles. My general feeling has been that the tyres are made to a British standard, tested by weights and measures, if it says 275/40/20 it is.  I'm not saying that the answers on here are deliberate attempts to cause worry, I am more interested in what owners have to say more so than the woman from black circles whose computer gave her an error message. 

In fact the car I have recently purchased was rung three different tread patterns, a crack side tyre wall and and a part worn when I got hold of it.  It's slowly coming back up to a reasonable standard. I knew all this when I bought it so it's not a shock to get it all sorted, but nit knowing and then finding out hankook don't make the same model for back just threw me. Especially after I searched the make on here and found members fitting them and being happy, now I see that they probable had smaller wheels and the model is available.

I have 22 inch wheels and ever since I put new tyres on it I have had the Dsc drop out if I give it to much go to quickly, I have matching rears but the fronts are completely different make and tread, i am that fed up I am actually getting rid of the 22 and going back to the bmw 20inch 177 stile with Bridgestone er30 start rated tyres. I am hoping it kicks my dsc issues in the ass, but the wrong tyres are certainly bad news for these things

I have had the dreaded "trans fail safe prog" message a few times now and each time I have has my codes read it comes back with "transfer box,tire tolerance" I have different make tyres front and back, still pairs but just different makes. It not a problem that's always there, I have been trying to notice what I am doing when it happens and the common theme I have now realised is I have to be gunning it either on a bumpy road ,lane switching/taking a fast corner or just sometimes gunning it from the lights, BUT like I say if I drive like my wife it goes all day with no dsc/4x4 warnings. I don't really like the 22inch wheels so they are going up for sale and I am looking out for the standard 20inch bmw and then I will stick some star rated tyres on and hopefully I can then drive how I want to. 

I got 4x Hankook Ventus ST from Blackcircles for about £600 - they are specifically 4x4 tyres.  They didn't show up for the X5 as they have a higher speed rating than the standard tyres so I had to manually choose them. 

They've been great, no complaints, a bit quieter than the expensive Michelin's too.