[racey1979]

Hi all, my first post so go easy Firstly, apologies if this is a repeat thread, I have read through dozens about tyres but still unsure what to do. Picked up a 2016 X3 35D at the weekend and so far really impressed. First SUV we’ve owned but far from first BMW, just sold a E91 335d after 5 years of pretty loyal service and currently also own an M240i. The X3 has staggered 20 inch 310M wheels, which to be honest are in need of a refurb. The tyres are Pirelli P Zero but are getting ready for replacing. I am quickly realising that finding good tyres appears to be a challenge and the offerings are very limited. I am getting lots of different opinions on what to buy, some are saying I absolutely MUST fit BMW star marked tyres otherwise I’ll goose the x drive system, but others are saying it doesn’t matter as long as the tyres are good quality, I replace all four and the rolling circumference of the tyres is within 1%. I’d also like to ditch the run flats if possible but again, this seems controversial. The tyres are 245 40 20 and 275 35 20. So far, if I have to stick to OE star marked, it looks like I’d pick Pirelli P Zero PZ4s which are run flat. However, I’ve never been a fan of Pirelli and from what I’ve read they wear really fast ? Not ideal at over £800 a set. I have also found Michelin Pilot Sport 4 run flat in the correct sizes BUT they are not BMW star marked. What’s even more frustrating is that they are Star Marked on certain sizes, just not those. Does it REALLY matter that much ? I’ve spoke to BMW who gave a very woolly answer, basically we can only recommend star marked but it’s up to you what you fit. Yeah, I know that I just want to know if I’m going to wreck my transmission ? To which they said they couldn’t say. As for non run flats, Michelin Pilot Supersport are available in star marked, but there’s no stock, of the rears I think. Michelin Pilot Sport 4 S also do a Star Marked tyre by the looks but not in both sizes and there’s no stock in the fronts. Driving me bloody nuts to be honest. Any advice on what to do is much appreciated, should I stick with Star Rated or would something like the Pilot Sport 4 run flat be suitable if the sizes are correct ?

Many thanks

Andy

[richardodn]

In the US, there is no such thing as star-marked tires. All that matters for us is size, load rating, & speed rating. Any tires that meet or exceed the factory ratings will work on your car with no drivetrain issues. In your case the ratings are:

245/40ZR20 99Y
275/35ZR20 102Y

Size
This is all your drivetrain really cares about. You want tires with the same rolling diameter so as not to induce stresses on the x-drive system it wasn't designed for.

Speed Rating
Although you may never go the speeds the tires are rated for, speed ratings are also a proxy for other features such as balance and heat dissipation. The Z rating is unimportant. That was the old way of designating speed rating and can be present or not. What is important is the Y designation. You'll want V, W, or Y rated tires with Y being the most desirable.

Load Rating
Load ratings specify how much load a tire can carry. BMW specified as low as a 96 rating for the X3 so that's your floor value.

To be honest, it sounds like more of a marketing thing. I suppose there is a possibility that there is a warranty reason for requiring star-marked tires. You'd have to check that for yourself.

As to runflats vs non-runflats, you'll just have to determine for yourself if you want to deal with the issues of not having a spare. Non-runflat tires are inherently better performing than equivalent runflats. Some people have simply gotten a spare tire that they haul around in the back.

Personally, I hated the runflats that were on mine. They never gave me any confidence on the road. How I dealt with the lack of spare was to:

A. have a compressor onboard. Most tire leaks are slow leaks. The plan is to pump the tires back up and drive to have them serviced.
B. if the leak is too fast for A, I have a tire plug kit in the car for a field repair.
C. if B can't take care of it. Fallback is an auto club membership for towing.

[e30lover318i]

Actually there is a star on us tires. BMW’s tires have this mark it just indicates that’s it’s a run flat tire approved by bmw. The only time this would matter is if you have a lease vehicle since bmw will not accept alternative tires.

But I’d 100% switch to non run flat as Richard stated it’s something you must decide as there are positives and negatives.

I have no run flats on my F25 and I purchased small compressor and a spare tire kit from another member on here.

[racey1979]

Thank you both for taking time to reply to me, that is really helpful. As mentioned, I have had a plethora of different opinions when speaking to BMW, tyre manufacturers and tyre fitters/dealers. I highly suspect most of the advice is based purely on arse covering, they don't want to risk any comeback so it's easier just to say "you must fit BMW Approved star marked tyres". I have decided to fit Michelin Pilot Sport 4 S non run flat tyres, in the correct sizes obviously. I have checked speed and load rating and all is good. You can actually get a star marked 4 S tyre but only in the 275 35 rear, it also gets a worse rating than the standard non star tyre for efficiency and wet performance. The standard tyre is C efficiency and A wet performance whereas the star marked tyre is E and B . One tyre outlet I spoke to sounded pretty clued up on the subject, they simply said it does not matter one iota about star rating or whether they are run flat or not. As long as the rolling circumference is the same or very VERY close, as in under 1% that it all that matters. If you buy all four tyres new, choose the correct sizes, use premium brands all round and don't mix them you won't have a problem with the transmission. I have noticed a mild shudder under heavy acceleration on the current tyres as well. I have measured the tread depth and the rears are worn more than the fronts, by about 2mm, so I am wondering if that's causing the shudder ? I will stress though it is very mild. On every BMW I have owned, ditching run flats has only ever had a positive effect, in some cases transformational like the E91 we had. I am aware of the risk/drawbacks and will negate accordingly. Thanks again.

[richardodn]

The difference in wear should have a negligible effect.

[racey1979]

Originally Posted by richardodn

In your case the ratings are:

245/40ZR20 99Y
275/35ZR20 102Y

Size
This is all your drivetrain really cares about. You want tires with the same rolling diameter so as not to induce stresses on the x-drive system it wasn't designed for.

Hi mate, I have ordered 4 x Michelin Pilot Sport 4 S tyres. Have you any idea what the tolerance between tyres (tires) is ? I have read up to 1% ? According to the handy US website tyre rack, the rolling circumference between F&R is about 0.66% different on the MPS4S. Over a mile it's 750 revolutions (front) vs 755 revolutions (rear). And I don't think those are generic numbers for the tyre sizes either as other tyres give different numbers. There are some U.K BMW X forums that really stress how important the use of BMW approved star rated tyres are. I don't get how it can be so different between countries lol X-D

[Whiteman]

My rear Pirelli RFTs replaced at 50,000km. Front will get to 60,000. Mostly highway driving but far from gentle - it’s a Beemer right?!

I can’t consider non RFT because I live in a part of Australia that is 100km between towns and stocks of any tyre that would fit (same profile as yours) is not on. It takes 2 weeks to find a replacement. If I could get a ready supply of tyres I would ditch RFTs. I still carry a full repair kit and compressor.

[stuboy2uk]

If you’re experiencing a mild shudder under heavy acceleration it sounds like the transfer box could already be damaged. I picked up my X3 in December and noticed a slight judder under heavy acceleration and after several trips back to the garage it was finally diagnosed as the transfer box and it was replaced under warranty. I’d get it back to the garage ASAP.

[racey1979]

Originally Posted by stuboy2uk

If you’re experiencing a mild shudder under heavy acceleration it sounds like the transfer box could already be damaged. I picked up my X3 in December and noticed a slight judder under heavy acceleration and after several trips back to the garage it was finally diagnosed as the transfer box and it was replaced under warranty. I’d get it back to the garage ASAP.

It was a private sale mate. And to be honest last few days of driving it I haven't noticed any judder, might have been in my head. Really impressed with it to be fair, it's our first SUV and I can't believe how nimble it is for something so large. I was expecting it to be a complete barge !