Tires....is this normal?

[Brazz]

I upgraded my run-flat 19in OEM M-Sport wheels/tires to 20in OEM M-Sport wheels with non run flat Michelin Pilot Sport A/S 3
(Fronts: 255/35/20 and Rears: 285/30/20). I like the ride of the non run flats better...thanks for all the advice. However, I notice there is a vibration under my seat around 78-80mph. I've had the tires road forced balanced twice at BMW and re-checked again at a wheel shop to see if the wheels were bent and there is still vibration. BMW did state that one of the rear tires was road force cleared but was at the borderline. Could that be the cause or is it that the tires are bigger than the OEM's and this slight vibration is due to tire size?
Help...

[HoustonRider]

its in the back tires (IMO) if you feel it in the seat, so your on the right track for sure. I would think the bal is the culprit, not the size.

Sometimes shops say ".25 oz off is good enough" until you get in on the highway. I have some 80lb tires on my truck and .25 oz is still enough to notice.

[M6-Coupe]

Originally Posted by Brazz

I upgraded my run-flat 19in OEM M-Sport wheels/tires to 20in OEM M-Sport wheels with non run flat Michelin Pilot Sport A/S 3
(Fronts: 255/35/20 and Rears: 285/30/20). I like the ride of the non run flats better...thanks for all the advice. However, I notice there is a vibration under my seat around 78-80mph. I've had the tires road forced balanced twice at BMW and re-checked again at a wheel shop to see if the wheels were bent and there is still vibration. BMW did state that one of the rear tires was road force cleared but was at the borderline. Could that be the cause or is it that the tires are bigger than the OEM's and this slight vibration is due to tire size?
Help...

About 2 years ago when I had my 2012 650i, I changed one of the rear tires that was puncture. After that I felt the same thing. Vibration under drivers seat specially at turns! So I think you have uneven tires.

[Brazz]

Originally Posted by M6-Coupe

About 2 years ago when I had my 2012 650i, I changed one of the rear tires that was puncture. After that I felt the same thing. Vibration under drivers seat specially at turns! So I think you have uneven tires.

By uneven do you mean the tires are not balanced properly???

[M6-Coupe]

Originally Posted by Brazz

By uneven do you mean the tires are not balanced properly???

No. The issue with my tires was:
1. The new one had more thread than the old one although both were the same brand and the same size.
2. The old one was worn unevenly. means the inside of tire was worn more than the outside. I believe you have the same issue. I know they may be brand new but probably one is defective. Check them out

[bmrfam]

Tires are not perfect creations and there are many times that you cannot get the weight in exactly the right place to balance a tire. I sold tires for a few years back in college and sometimes there are just bad ones. If your problems are really the tires, they are considered defective. You paid for a product that rolls smooth and lasts a while and they may have not delivered on the first. If you wanted shaking tires, you could have bought used. Most places will fight you a bit on it but if you press hard enough, they will usually accommodate. Since you have new wheels, they could equally be the culprit. The machine and techniques they use to judge wheel roundness is a joke. I saw plenty that looked ok when you spun them but no mater what tire was mounted, they still had a shake and the same tire on another wheel was fine.

Make them put two newly balanced tires on the wheels for a couple of days to prove it is not the tires. If the new ones still shake, then the wheels or something else is the issue. If they stop shaking, you get to keep the good tires.

Tires and wheels are a bit of an art and unfortunately sometimes the people helping you have not mastered the art.

Tire size has nothing to do with shakes. A circle is still round no matter how big it is. It sounds like you have an oval in there someplace (wheel or tire).

[Brazz]

Thank you. I called BMW for a replacement tire. They are going to get back to me. We'll see.....

[doug_999]

Two things
1. I had a slight vibration after getting one of my fronts replaced by BMW. Actually worse than slight. I took it to Discount Tire and the rebalanced all of my wheels at no charge. The tech told me later that my front wheel (the one with the tire replaced) was slightly bent/out of round and he was only able to notice it when watching the balancing machine (could see the tire go up/down slightly). The vibration was much MUCH better after Discount Tire balanced it*
2. I switched to non-rfts shortly after this and still had the vibration. However, it seems to either be gone or I have gotten totally used to it.

*I don't think BMW dealers are great at mounting/dismounting/balancing tires. If you have a Discount Tire near you I believe they will do it no charge (or maybe they did it because I'm a customer?). Give that a try if your new tire does not work out.

[WWnyc]

Originally Posted by bmrfam

Tires are not perfect creations and there

Tire size has nothing to do with shakes. A circle is still round no matter how big it is. It sounds like you have an oval in there someplace (wheel or tire).

SIMPLE, ELEGANT, TO THE POINT. BEAUTIFULLY SAID.

[Brazz]

Originally Posted by WWnyc

SIMPLE, ELEGANT, TO THE POINT. BEAUTIFULLY SAID.

Good point. Never considered that the service techs at BMW wouldn't be good at balancing tires but it makes sense, they are not a tire shop... I'm still waiting to hear back on whether they will replace the current one. I buy a lot from Discount Tire as well. I may take it to them when I get my new one.

Thanks....

[Brazz]

Totally confused now. I know it's the passenger rear wheel/tire combo that is causing the vibration. Put on a new tire and the same problem exists. Took the wheel to 2 separate wheel shops and they both say the wheels are not bent. Then why the vibration from the rear passenger tire/wheel at 70mph??? Help?

[doug_999]

There is a chance the person installing the wheels bent something - also a small out of round on the actual wheel will cause an issue.

I hate to say this, but you need to find a replacement wheel and try that. If that also causes an issue, then it is the car having an issue

[33WDM]

This is an incredibly frustrating issue.

I have a 2015 650i GC with M-Sport package and 20" Dunlop RFT's.

I have the same complaint - At 70-80mph, the car "shakes" (probably too strong a word). Issue is not in the steering wheel - it's "a chassis vibration" - common sense tells me it's an out of balance wheel/tire(s).

I took back to dealer at 1900 miles - service manager drove it and immediately agreed there was an issue.

They force balanced all 4 tires/wheels and actually replaced 3 tires and 1 wheel!

Got the car back, issue remains!

I recently took car to Discount Tire - had them force balance all 4 - they said tires/wheels were as close to perfect as they could get?!?

I've played around with tire pressures, I've tried to see if the issue was possibly a transmission issue - but same phenomenon exists whether I am in Comfort mode or Sport mode, accelerating or coasting, going straight or turning. The issue shows up on every kind of highway in my area as well.

Frustrated!!

Any other ideas what could be causing this, or is this something we just "live with"?

[Brazz]

Originally Posted by 33WDM

This is an incredibly frustrating issue.

I have a 2015 650i GC with M-Sport package and 20" Dunlop RFT's.

I have the same complaint - At 70-80mph, the car "shakes" (probably too strong a word). Issue is not in the steering wheel - it's "a chassis vibration" - common sense tells me it's an out of balance wheel/tire(s).

I took back to dealer at 1900 miles - service manager drove it and immediately agreed there was an issue.

They force balanced all 4 tires/wheels and actually replaced 3 tires and 1 wheel!

Got the car back, issue remains!

I recently took car to Discount Tire - had them force balance all 4 - they said tires/wheels were as close to perfect as they could get?!?

I've played around with tire pressures, I've tried to see if the issue was possibly a transmission issue - but same phenomenon exists whether I am in Comfort mode or Sport mode, accelerating or coasting, going straight or turning. The issue shows up on every kind of highway in my area as well.

Frustrated!!

Any other ideas what could be causing this, or is this something we just "live with"?

It is something that I'm learning to live with. I've done all things you have done plus taking the car to two different wheel shops to check for bent wheels. Nothing. I upgraded to 20's I didn't have the issue with the 19's. Strange. No answers. Otherwise an excellent car.