Tyre Sizes

[Matt2306]

Hi, probably a question that is answered elsewhere on the forum, so apologies.

I recently purchased an X5 E53 3.0D sport, love it so far, lots of work done and to do, anyway, its currently running on 285/45/19 tyres front and rear, is this correct or should it be running staggered?

Tyres are all good with loads of tread so don't want to replace, but also don't want to damage the transfer box as I have seen posts about running the wrong tyres doing.

TIA, Matt

[Greydog]

Morning Matt

Check the rim sizes (stamped on the inside of the rim) from memory my 4.4 on 19" staggered rims was front 255x 50x 19x 9j rear 285x 45x 19x 10j some previous owner may have fitted the wider rear wheels to the front as well for aesthetics

The staggered set up does need careful sourcing of tyres if there is to much variance in diameter .front to rear damage will occur to the transfer box and transmission. Having a square set up (same rims front and rear) reduces but doesn't  take the risk away it is better to have same make on all corners preferably with similar wear rate.

Good little trick to check tyre rolling radius is make a chalk mark on the tyres front and rear where it meets the floor, roll the car forward one rotation all the chalk marks should be pretty much were you want them if one or more isn't you have a potential problem. 

Dave

 

[Matt2306]

Hi Dave

 

That's great, thanks, so running the same size all the way round will be fine 👍 I'm glad about that as all tyres have good tread, so didn't want to change any of them.

[Greydog]

Morning Matt

The same size tyres are only OK if the rim sizes are correct a 285x45 tyre on a 9j rim will give a different rolling radius to a 285x45 tyre on a 10j rim. So check the rim sizes, also check the spare if you have one chalk test is good, my 4.6 has a space saver spare but I also carry a couple of cans of tyre goo and a compressor, (touches wood) I haven't needed them. So just make sure you have the same size rims front and rear.

Tyre life on the X5 is effected by the condition of the suspension bushes and links they are only good for about 80k (my own experience) Front suspension brake reaction arms wearing will cause brake shudder. I poly-bushed mine Rear I rebuilt with standard bushes about 3hrs a side with tea and biscuits. I included the swing arm bushes (BMW will tell you you need the complete arm) I used kits from Ebay then 4 wheel alignment and all good.

Certainly a square set up makes matching front to rear rolling radius much easier 

Dave

[Matt2306]

Hi Dave

Thanks for the info, only just had chance to take the wheels off while I sort a couple of other things.  I'm still a bit unsure, I've checked the markings inside the wheels and the fronts are marked E 9Jx19  the rears are marked E 10Jx19 the car is on 285/45/R19's all the way round.

 

Haven't done the chalk test yet, will do that once I've put the beast back together.  But I'm guessing from the markings that I should be running 255's on the front rather than 285's??

 

Sorry to be a halfwit with this!!!

Cheers Matt.