[Dr.AD]

Originally Posted by graaja

Update:

I got a notification on the instrument cluster that the front brake pads need to be replaced in 1700km, when the ODO was at 20900km. This is quite surprising as the iDrive was showing 17000km as expected life when the Odo was at 19000km. As I have seen similar experience from other owners in some other threads, I think the brake pad life predicted by iDrive should be taken with a bucket of salt. Will be taking the car to the workshop this week or next to have the brake pads replaced.

I wonder if this happens more particularly about the front brake pads, maybe because of more excessive and non-linear (over time) wear of the front pads as compared to rear brake pads?

In my case, I had a similar experience with front brake pads. At about 15000 km odometer reading, the front brake pad life shown in iDrive was 9000 km. However, it rapidly decreased after that, and I ended up changing the front brake pads at about 18000km, when the shown life was about 700km only.

On the other hand, the rear brake pad life shown in the iDrive had been decreasing more consistently and more or less linearly all the time till when I changed the rear brake pads at 27000km. There was never any sudden drop in the rear brake pad life.

[nerd1200]

Originally Posted by Dr.AD

I wonder if this happens more particularly about the front brake pads, maybe because of more excessive and non-linear (over time) wear of the front pads as compared to rear brake pads?

Similar experience in my Laura. The life of the rear brake pads are close to double that of the front's. Apparently, the hydraulic system is biased towards the front since the larger discs and pads provide better stopping power compared to the rears.

Here are some insightful answers on a Quora question.

[Dr.AD]

Originally Posted by nerd1200

Similar experience in my Laura. The life of the rear brake pads are close to double that of the front's. Apparently, the hydraulic system is biased towards the front since the larger discs and pads provide better stopping power compared to the rears.

Definitely. It is given that the front brakes take most of the braking load because of the weight transfer on the front during braking.

The point of discussion here is not that the rear brake pads have double the life than the front brake pads. The main point is that the wear in the rear brake pads seem to be linear enough for iDrive to predict well, whereas the wear in the front pad seems to be nonlinear and the iDrive is not able to predict it well. In other words, the predicted life of front brake pads decreases significantly all of a sudden, whereas that did not happen for the rear brake pads.

I was just wondering if this is just my experience or if others have also noticed this.

[graaja]

Update:

My search for the rear tires still continues. I had ordered 255/45/R18 Continental Conti Sport Contact 5. 2 weeks have passed since I placed the order, the tires have not arrived yet and the dealer says even Continental is not giving any guaranteed time of arrival of these tires. As my car is lying idle, I need to figure out something to get the car back on road. Following are some of the options I have.

Option - 1:
The front tires are 225/50/R18. This size is readily available. The front tires have another 2k to 3K life left. I fix the new 225/50/R18 in the rear wheels and keep driving the car. When the 255/45/R18 tires arrive, and when the front tires need replacement, I fix the 255's in the rear and shift the 225's to the front.

Option - 2:
Go tubeless. 255/45/R18 is available in Michelin Primacy HP. However, 225/50/R18 is not available in Primacy HP. So, I will have to find a different model for this. But I am not convinced having two different models for front and rear.

Option - 3:
Get rid of the staggered setup and go with 225/50/R18 all round. This will solve the problem of tire availability. But it may affect the handling properties of the car. Right now, I am super happy with the M Sport suspension + staggered tires setup, and do not want to compromise on this.

I could go with Option - 1 and see how the all round 225/50/R18 setup behaves. If it does not degrade the ride and handling, then I could just continue with 225's all round. Else wait for the 255's to arrive and go back to staggered.

I have also asked my tire dealer to check if Pirelli has any RFT model with 255/45/R18.

Are there any other options that I am missing? Are there any other tubeless options where I get both 255's and 225's? Or any other RFT options?

[lamborghini]

Have you thought about going the 225 in front, and 245 in rear route?

245/45R18 should be a lot more common and easier to procure than the 255/45R18 while not hampering the handling significantly either.

[graaja]

Originally Posted by lamborghini

Have you thought about going the 225 in front, and 245 in rear route?

245/45R18 should be a lot more common and easier to procure than the 255/45R18 while not hampering the handling significantly either.

Thank you for the suggestion. I have not considered changing the size yet.

But a 245/45/R18 in the rear would be a lot closer to the current set up than going all round 225's. Between 255/45 and 245/45, there is a 1.1% error in diameter which should not be a big problem I guess. I will now add this option as well.

[lamborghini]

Originally Posted by graaja

Thank you for the suggestion. I have not considered changing the size yet.

But a 245/45/R18 in the rear would be a lot closer to the current set up than going all round 225's. Between 255/45 and 245/45, there is a 1.1% error in diameter which should not be a big problem I guess. I will now add this option as well.

On my 328i, I am using 245/45R18 all around.

Ditched the RFT for better softer rubber that has helped the ride & handling (using Pirelli P Zero, but Michelin PS4 is that much better from reviews - both available in the size).
Yes, it won't be as practical especially on the longer journeys - but with the stiffer suspension, it would balance out the city ride a fair amount better.

Personally, after using CSC5 on the E60 525d, I was quite happy with their grip & overall nature but this was a while back - I think there are better alternatives in the market today.

[Santoshbhat]

I would second lamborghini's suggestion to go for 245/45 tubeless all round. Advantages...
1) Comfier and quieter ride.
2) Lower cost
3) Long life from the tyres. Tubeless tyres tend to last longer than RFTs
4) Possibility of doing 4 tyre rotation at fixed intervals, extending life further

My X3's first set of Pirelli RFTs lasted only 25K kms. Thereafter I switched to Pirelli tubeless and love the feel of the car so much that I cannot imagine going back to RFTs. The tubeless Pirellis have done 22k kms so far and still look like they have almost 50% life left! I do a 4 tyre rotation every 7.5k kms.

[Axe77]

Originally Posted by Santoshbhat

I would second lamborghini's suggestion to go for 245/45 tubeless all round. Advantages...

1).

How do you protect yourself against punctures?

[graaja]

Originally Posted by lamborghini

Ditched the RFT for better softer rubber that has helped the ride & handling (using Pirelli P Zero, but Michelin PS4 is that much better from reviews - both available in the size).
Yes, it won't be as practical especially on the longer journeys - but with the stiffer suspension, it would balance out the city ride a fair amount better.

Originally Posted by Santoshbhat

I would second lamborghini's suggestion to go for 245/45 tubeless all round...

Thank you Santosh and lamborghini. I understand how much comfortable tubeless tires would be compared to RFTs. But I am hesitant to go tubeless because of the lack of proper spare wheel and the long drives I do with family (on very bad roads sometimes). RFTs give me that peace of mind.

I also found the Conti Sport Contact 5 SSRs to be quite comfortable and silent and did not feel them to be harsh at all. That is the reason why I am giving first preference to RFTs

Originally Posted by Axe77

How do you protect yourself against punctures?

That is my main worry!

[Hayek]

Originally Posted by graaja

245/45/R18 in the rear would be a lot closer to the current set up than going all round 225's.

The other option would be looking at the 245/50/R18 - which is the OE tyre on the X3. Slightly higher error of 2% but well within tolerable limits. I would stick to runflats - the technology is materially safer.

[Santoshbhat]

Originally Posted by Axe77

How do you protect yourself against punctures?

Oh, I just assumed all you guys carry a space saver in your cars. Ability to traverse 80 kms on a flat RFT is just not good enough in our country. I have carried a space saver in my car right from day one, even though I was on run flats for the initial period. I could never take the chance of being stranded somewhere far away with family with just 80 kms in the bank.

Tubeless tyres + puncture repair kit + tyre inflator + space saver does the trick for me.

Originally Posted by Hayek

I would stick to runflats - the technology is materially safer.

Agree RFTs carry an extra degree of safety compared to conventional tubeless tyres. But I always find it quite strange that when someone is evaluating a car in the luxury segment among BMW, Merc, Audi, Volvo etc... the fact that a particular model does not come with RFTs is very rarely a deal breaker. Say if one chose the Audi over the BMW, he wouldn't, for instance, think of switching to RFTs from the company provided tubeless tyres for that extra layer of safety. But, if he were to buy the BMW, he would rather suffer the harsh RFT and not switch to tubeless because he does not want to compromise on safety. Forget changing to tubeless on new cars , I am yet to come across someone deciding to pick run flat tyres on their non BMW cars when it is time to replace worn tyres.

[Chethan B G]

Originally Posted by Santoshbhat

Agree RFTs carry an extra degree of safety compared to conventional tubeless tyres. But I always find it quite strange that when someone is evaluating a car in the luxury segment among BMW, Merc, Audi, Volvo etc... the fact that a particular model does not come with RFTs is very rarely a deal breaker. Say if one chose the Audi over the BMW, he wouldn't, for instance, think of switching to RFTs from the company provided tubeless tyres for that extra layer of safety. But, if he were to buy the BMW, he would rather suffer the harsh RFT and not switch to tubeless because he does not want to compromise on safety. Forget changing to tubeless on new cars , I am yet to come across someone deciding to pick run flat tyres on their non BMW cars when it is time to replace worn tyres.

Interesting!

One question: Are the alloys used for RFT any different than the alloys used for Tubeless tyres? Structurally that is.

I had to change a Tyre (RFT) just because it had a puncture! Even though I had BMW Secure, I had to spend 10K from my pocket. A minimum of 10K per puncture is absurd!


@Ganesh: Option - 2: Go tubeless. 255/45/R18 is available in Michelin Primacy HP. However, 225/50/R18 is not available in Primacy HP. So, I will have to find a different model for this. But I am not convinced having two different models for front and rear.

In a Staggered setup, the difference in Tyre width does not make the tyres uniform all-round. Wider tyres at the back with higher traction and grip is meant to be supreme. Therefore, different brand of Tyres for front does not create a problem IMHO. They are anyways supposed / designed to be different.

[Hayek]

Originally Posted by Santoshbhat

Oh, I just assumed all you guys carry a space saver in your cars. Ability to traverse 80 kms on a flat RFT is just not good enough in our country.

Agree RFTs carry an extra degree of safety compared to conventional tubeless tyres. Say if one chose the Audi over the BMW, he wouldn't, for instance, think of switching to RFTs from the company provided tubeless tyres for that extra layer of safety. But, if he were to buy the BMW, he would rather suffer the harsh RFT and not switch to tubeless

I do carry a space saver everywhere I go. However, I am not capable of using a puncture repair kit myself.

The second point you make is an interesting one - it is a classic example of the endowment effect - where we get psychologically attached to what we have even if we would not have bought it in first place.

[graaja]

Thank you friends, for all your inputs. After going through inputs from Santhosh, lamborghini and Chethan, I decided to check out the tubeless option as well (though my preference is still RFT, maybe because of the endowment effect that Hayek pointed )

Though 255/45/R18 and 245/45/R18 are available in tubeless, I could not find 225/50/R18. The only way I can go tubeless is by upsizing the front tires to 24/45/R18 which I want to avoid (will keep this as last option). I want to keep the staggered setup.

Back to RFTs, I have found two options in RFTs

1. 225/50/R18 Conti Sport Contact 5, 245/45/R18 Conti Sport Contact 3
2. Pirelli P7 CINT 225/50/R18 and 245/45/R18

And there is one more option. 255/45/R18 in Conti Sport Contact 5 SSR are available in tirerack web store. Cost is $450 for two tires. A friend of mine had a good experience with them importing some tires. I have written to them to find out what is the shipping cost for shipping to India. Will decide the final option once I hear back from tirerack.

Phew! Never thought it would be so tough changing tires on the BMW!!

EDIT: I have also talked to Nikhil and waiting for his opinion on any other options I may have.