A star tyres , myth or fact

[kkx5]

Tyres should wear equally. If they dont, check your wheel alignment.

[Spandex]

I’m not talking about wearing unevenly across the tread of a single tyre. I’m talking about the fact that the front pair will wear at a different rate to the rear pair. Nothing to do with alignment.

[kkx5]

The fact? Mine do wear at the same rate on all 4 tyres. Always did.

[Spandex]

There are numerous threads across various forums where people discuss uneven wear front to back on these cars. It’s not uncommon.

Regardless, it’s a hypothetical question. How the treads end up different isn’t really relevant. Do you know the answer?

[Graeme]

Interestingly,

I have a set of Vredestein Wintrac Extremes non-runflat and non * (but they have a circumference that is less than 5mm different front to rear) on 255x50x19 fronts and 285x45x19 rears that have now done 20000 miles over 4 winters and they are wearing evenly. 
Each April I swap them with Good Year Eagle F1 * Runflats and after 18000 miles in two summers, the rears are down to 2.5mm and the fronts are still 5-6mm.  In the summer I do many more miles on motorways and dual carriageways than in the winter. So my assumption is on straight roads the X drive allows more energy to power the rear wheels so they wear more quickly.

Anecdotal, but true!!!

Graeme

[asoni]

So I’ve bitten the bullet and gone for a new set of Michelin latitude sport 3’s all round.

I am convinced that as long as all 4 are changed, I should not have any issues. I also want to scratch the itch and see what  normal tyres feel like on this car. End of the day if there is not a huge difference, I can go back to run flats next time and benefit from the added convenience.

Anyway in terms of the tyre I’ve chosen, what do you guys think? It’s supposed to be a great tyre and is fitted to a lot of top end cars from factory like new x5, Volvo, Porsche etc.

[IanP]

Nothing wrong with those tyres. You could always compare them side by side before fitting and See if there is a noticeable difference in diameter. If not then I reckon all will be good.

[Spandex]

If you can get a photo of the fronts next to the rears on a flat surface for comparison, that might help others considering them too.

[Icicles]

[quote="asoni"]
So I’ve bitten the bullet and gone for a new set of Michelin latitude sport 3’s all round.

I am convinced that as long as all 4 are changed, I should not have any issues. I also want to scratch the itch and see what  normal tyres feel like on this car. End of the day if there is not a huge difference, I can go back to run flats next time and benefit from the added convenience.

Anyway in terms of the tyre I’ve chosen, what do you guys think? It’s supposed to be a great tyre and is fitted to a lot of top end cars from factory like new x5, Volvo, Porsche etc.
[/quote]I currently run the Michelin Latitude Sport 3 tyres non run flat. I run the 20" staggered set-up
Im very happy with the results.
Quiet. Smooth, not as bumpy.
I run 44psi front 42 psi rear.
Wearing great

Chris

Sent from my SM-G930F using Tapatalk

[asoni]

Cheers, sounds good and can’t wait to try them. I know psi is meant to be higher for non run flats but doesn’t that sound too high?

[Icicles]

I listen to what the guy says who does my wheel alignment. Been seeing him for over 25 years. Very highly respected in the motorsports sector
I do as i'm told lol.
He even knows if I have had the wheels off the car. And wants to know who's been working on it.
On the side wall it is 50psi Max.
I'm not concerned

Chris

Sent from my SM-G930F using Tapatalk

[asoni]

Fair enough lol, makes sense!

[Chrispy]

Re this, (and this is my thought processes out loud)......I'm sure it was mentioned earlier in the thread, if * marked batches are compared to ensure RR consistency across a staggered setup.  So, for us we know that on a 19" setup (using mine as an example with diddy 223 peasant wheels ) it would be a 255/50/19 front and a 285/45/19 rear. 

So, do they compare every 255/50/19 to every 285/45/19 to ensure the same RR?  Or do they sample the odd one from a batch?  And how many other variations are there?

Or are we simply saying that every 255/50/19 has to conform to a much more stringent QA process to ensure adherence to a specific RR (and weight), and the same for every 285/45/19?  This would make more sense, although how much closer these tyres would be to pre-defined sizes than other "premium" brand non * marked tyres is debatable considering manufacturing methods would be the same or very similar across the board.  Either that or they are they subject to the "shaving" process afterwards to ensure their size if they're a tad on the big side. Not sure how they'd handle ones that are too small though, and if they are "shaved" how much tread is lost?  Or they're simply rejected if they don't stack up, meaning potentially a lot of waste which makes bad business sense.  Otherwise the tooling for * marked would need to be fairly different to non * marked, perhaps warranting a completely different production line?

Simply enforcing tighter QA processes for * marked vs non * marked seems the most plausible to me considering Bridgestone make lots of tyres for all sorts of different applications, and produce the * Dueller HP's running on mine at the moment and also non * marked equivalents too.  So only the best will cockadoodle doo?

I doubt we'll ever know and much of this is conjecture, with anecdotal evidence on both sides, however I do have a few thoughts:

1. The car comes as standard with run flats, and you can drive at say 50mph roughly with a flat for X amount of miles to get it replaced.  As such the RR on that tyre will be substantially lower than all other tyres at that point, and it will have been lower for a period anyway for the TPS (ABS based) to have picked it up.  Does this cause an issue with the transfer case?  I for example had a screw in my tyre at the weekend, causing a slow puncture and my TPS came on.  Quick top up and I was on my way again (got it repaired the day after) but at no point before the TPS came on did I suspect there was anything wrong prior to this (whining diff etc)

2. The aforementioned natural differences in RR front to back due to wear and possible pressure variations (I've read it quite a bit that the rears wear faster than the fronts).  My E91 used to chew through rears at almost twice the rate of the fronts, possibly due to enthusiastic driving and the fact it was pure RWD, no torque split.....would these exceed or match the differences as a result of manufacturing / poor QA across tyre batches?

[asoni]

The latitude sport 3's have now been fitted and I've done a bit of driving.

At higher speeds, there is a small but definite difference when going over ruts, pot holes and imperfections in the road.

At normal lower speeds however, there is a huge difference and the car feels so much more softer and comfortable. Transformed might be too strong a word but it's not far off that. 

Well worth it on initial impressions.

[graemeX5]

Hi
This is what BMW say on their website re star marked tyres

Why do you need BMW Star Marked Tyres?

Did you know that over a third of all enquiries and MOT failures are related to tyres? That’s why having the right tyres is paramount. BMW Star Marked tyres are designed in collaboration with leading tyre manufacturers, meaning they not only provide a smooth drive and optimum grip, but also ensure that they are made specifically for your BMW model.

Also a further search says this
A FEW QUESTIONS ANSWERED.
Question: What are BMW Star Marked tyres?

Answer: The star marking is the BMW stamp of approval. All BMW Star Marked tyres have been tested and developed in partnership with leading tyre manufacturers to ensure they harmonise with your BMW in the best way possible ensuring optimum performance, comfort and safety.

Also on. piston heads they talk about the circumference and also the weight of the tyres being the same on star marked tyres.
And this is one exert from the discussion

I ended up chasing information about star marked tyres for my E83 X3 back to BMW in Germany because of a shortage of the required Dunlops at the time. That's when I found out that the staggered fitment tyres were manufactured to match on both rolling radius AND weight.
Absolutely shocking.
So in theory even the correct star marked tyres could cause problems if you have a brand new axle pair at one end and 80% worn pair on the other axle (!!!).

So I guess as the tyres are tested by BMW and it guarantees they work with your BMW.

If they are correct and the weight is also considered does that mean physics come into play?

Are we then considering the force that would need to be roughly the same at all four corners, in order to avoid problems in the drivetrain as they are linked. If they are the same it would ensure they turn at the same rate, rather than one axle trying to rotate faster than the other. I wish Id learned physics at school

I may try and ask one of the master techs at BMW on Saturday which may have more info

Graeme