Tyres Tyres Tyres!

[Nanu]

Thats a good price for the rears. I have seen the same advertised for as much as £60 more each.

Will be needing 2 new rears in about another 1K or so. Will definitely be putting on the Conti 7s from all the good feedback.

Wonder if it will balance the fuel consumption concerns by having the new Conti 7s on the rear and having the Michelins still on the front for another 10k miles thats left on them?

The difference in fuel consumption must be relatively marginal…I’d be more concerned with having some less grippy front tyres for 10k miles..

There is nothing wrong with the grip on the fronts. It will just mean fronts good rears better. No intention of spending nearly £300 to replace perfectly good tyres

[B21]

Thats a good price for the rears. I have seen the same advertised for as much as £60 more each.

Will be needing 2 new rears in about another 1K or so. Will definitely be putting on the Conti 7s from all the good feedback.

Wonder if it will balance the fuel consumption concerns by having the new Conti 7s on the rear and having the Michelins still on the front for another 10k miles thats left on them?

The difference in fuel consumption must be relatively marginal…I’d be more concerned with having some less grippy front tyres for 10k miles..

There is nothing wrong with the grip on the fronts. It will just mean fronts good rears better. No intention of spending nearly £300 to replace perfectly good tyres

Of course it’s your prerogative….as you state the grip levels are different and will be more marked depending on changing conditions ..enjoy ..

[Schaef]

Thats a good price for the rears. I have seen the same advertised for as much as £60 more each.

Will be needing 2 new rears in about another 1K or so. Will definitely be putting on the Conti 7s from all the good feedback.

Wonder if it will balance the fuel consumption concerns by having the new Conti 7s on the rear and having the Michelins still on the front for another 10k miles thats left on them?

When my rear tires were worn out I switched to Pirelli. I have had quite a few problems with the tracking system with Michelins at the front and Pirelli tires at the rear. Every bend I took a little faster than normal, the car started to correct the car via the brakes, even though I was not going extremely fast. Very weird. Then I replaced the front tires for Pirelli and then this problem was over. I think it has to do with the sidewall of the tire, where Michelin's are a bit firmer than Pirelli's, which makes the car think that the car is going to break away.

That is my experience with two different brands of tires front and rear.

[ori]

Just replaced my rears with continental sport contact 7.

What a difference. I can actually accelerate without spinning the wheels. I mean I could with the mits, but they required me to warm them up.

You were right argyle Andy. Should have done it a long time ago!

[Nanu]

Just replaced my rears with continental sport contact 7.

What a difference. I can actually accelerate without spinning the wheels. I mean I could with the mits, but they required me to warm them up.

You were right argyle Andy. Should have done it a long time ago!

Have you just replaced the rears with the Conti 7s? What do you have on the fronts?

[q96169we]

Thats a good price for the rears. I have seen the same advertised for as much as £60 more each.

Will be needing 2 new rears in about another 1K or so. Will definitely be putting on the Conti 7s from all the good feedback.

Wonder if it will balance the fuel consumption concerns by having the new Conti 7s on the rear and having the Michelins still on the front for another 10k miles thats left on them?

When my rear tires were worn out I switched to Pirelli. I have had quite a few problems with the tracking system with Michelins at the front and Pirelli tires at the rear. Every bend I took a little faster than normal, the car started to correct the car via the brakes, even though I was not going extremely fast. Very weird. Then I replaced the front tires for Pirelli and then this problem was over. I think it has to do with the sidewall of the tire, where Michelin's are a bit firmer than Pirelli's, which makes the car think that the car is going to break away.

That is my experience with two different brands of tires front and rear.

I think the main issue is the different front and rear tyre size (assume you have 255 front and 275 rear). The tyre size spec allows some variation even if both tyres are 275/35R19. For example, my G31 rear is same size as G29 but one with p-zero and the other is MPSS. When I put them side by side, visually, the p-zero is much narrower than the MPSS despite both are 275/35R19. Usually, same brand same model of tyre stick to the same variation but different brand or different model of tyre will have different variation. Consequently, if you mix tyres front and rear, the DSC wheel speed sensor will read a value that can make the ECU think it needs to do some correction, as the ECU does not know you've put different tyre on. As the ECU is only callibrated to the star-marked defined tyre size variation, in theory, if your front and rear tyres are different brand but all are star-marked, this issue should go away.

[B21]

Thats a good price for the rears. I have seen the same advertised for as much as £60 more each.

Will be needing 2 new rears in about another 1K or so. Will definitely be putting on the Conti 7s from all the good feedback.

Wonder if it will balance the fuel consumption concerns by having the new Conti 7s on the rear and having the Michelins still on the front for another 10k miles thats left on them?

When my rear tires were worn out I switched to Pirelli. I have had quite a few problems with the tracking system with Michelins at the front and Pirelli tires at the rear. Every bend I took a little faster than normal, the car started to correct the car via the brakes, even though I was not going extremely fast. Very weird. Then I replaced the front tires for Pirelli and then this problem was over. I think it has to do with the sidewall of the tire, where Michelin's are a bit firmer than Pirelli's, which makes the car think that the car is going to break away.

That is my experience with two different brands of tires front and rear.

I think the main issue is the different front and rear tyre size (assume you have 255 front and 275 rear). The tyre size spec allows some variation even if both tyres are 275/35R19. For example, my G31 rear is same size as G29 but one with p-zero and the other is MPSS. When I put them side by side, visually, the p-zero is much narrower than the MPSS despite both are 275/35R19. Usually, same brand same model of tyre stick to the same variation but different brand or different model of tyre will have different variation. Consequently, if you mix tyres front and rear, the DSC wheel speed sensor will read a value that can make the ECU think it needs to do some correction, as the ECU does not know you've put different tyre on. As the ECU is only callibrated to the star-marked defined tyre size variation, in theory, if your front and rear tyres are different brand but all are star-marked, this issue should go away.

Two contradictory points…the G29 DSC was revised over the E89 version to allow widely different rolling circumferences front and rear ..but…just cause a tyre is star marked doesn’t mean it complies with an agreed international standard..only complete sets from a certain model of tyre from a certain manufacturer comply..for a fact MP4SS and SC7 for BMW star are not the same absolute dimensions..and in this case the discussion was about off the shelf SC7s anyway..so tyre construction and absolute dimensions are not guaranteed…compared to a match set of star rated tyres….

One of the reason they are star rated is for reduced rolling resistance ..ie fuel economy…

[Schaef]

Just one more thing, I have always bought the tires with the BMW coding (star).

https://www.youtube.com/watch?v=COA630Juf_U

[Nanu]

Thanks guys but too technical for my brain. Will wait for Ori to respond.

All I want to know is will I notice anything adverse to having Conti 7s on the rear and used Michelins on the front? When the front ones need changing then will put Conti7s on the front if not.

If there are adverse effects will just replace the rears with like for like

[ori]

Just replaced my rears with continental sport contact 7.

What a difference. I can actually accelerate without spinning the wheels. I mean I could with the mits, but they required me to warm them up.

I’ve only replaced the rears for now. My fronts still have 4mm of tread so I’ll replace when needed. Still on pilot sports up front.

You were right argyle Andy. Should have done it a long time ago!

Have you just replaced the rears with the Conti 7s? What do you have on the fronts?

[ori]

Thats a good price for the rears. I have seen the same advertised for as much as £60 more each.

Will be needing 2 new rears in about another 1K or so. Will definitely be putting on the Conti 7s from all the good feedback.

Wonder if it will balance the fuel consumption concerns by having the new Conti 7s on the rear and having the Michelins still on the front for another 10k miles thats left on them?

When my rear tires were worn out I switched to Pirelli. I have had quite a few problems with the tracking system with Michelins at the front and Pirelli tires at the rear. Every bend I took a little faster than normal, the car started to correct the car via the brakes, even though I was not going extremely fast. Very weird. Then I replaced the front tires for Pirelli and then this problem was over. I think it has to do with the sidewall of the tire, where Michelin's are a bit firmer than Pirelli's, which makes the car think that the car is going to break away.

That is my experience with two different brands of tires front and rear.

I think the main issue is the different front and rear tyre size (assume you have 255 front and 275 rear). The tyre size spec allows some variation even if both tyres are 275/35R19. For example, my G31 rear is same size as G29 but one with p-zero and the other is MPSS. When I put them side by side, visually, the p-zero is much narrower than the MPSS despite both are 275/35R19. Usually, same brand same model of tyre stick to the same variation but different brand or different model of tyre will have different variation. Consequently, if you mix tyres front and rear, the DSC wheel speed sensor will read a value that can make the ECU think it needs to do some correction, as the ECU does not know you've put different tyre on. As the ECU is only callibrated to the star-marked defined tyre size variation, in theory, if your front and rear tyres are different brand but all are star-marked, this issue should go away.

What you say makes sense in theory, but then tyre wear would cause a similar issue no? The car doesn’t know tyre wear and so it must detect slippage in other ways. I presume using g sensors and other wheel sensors.

The rear end grip I am not getting with my new tyres from cold is significantly better. I can put my foot down and the wheels don’t spin. Previously, accelerating was more challenging.

[ori]

Forgot to mention. You can select other tyre in the idrive so the car knows it’s running different non star marked tyres.