New rear tires, sharp off ramp and DTC kicked in hard

[STR3T]

So I've put 5k miles on this '09 since April. The RFT's treads were getting pretty weak on the rears so I had a local shop put on a pair of Cont Extreme DWS.

Still have ~7mm of tread on the fronts, so did not replace those yet.

Drive in to work this am I do notice a little more lane drift than I had prior. Read about that on some of the more negative Z4 reviews.

Bigger issue was taking an off ramp at ~10mph over the recommended pace...pretty typical speed on any newer vehicle really. But the engine slowed down, DTC lights flashed, etc. Was about to freak out but then wondered about tire break-in period? Think these are too new/slick and just need some more miles on them or some other issue, maybe running vastly different fronts(RFT's with much less tread) vs. rears (non-RFTs with new tread)?

[Lurcher]

Not really a break-in on street tires - no need to heat cycle like slicks. Likely just hit a slick spot or pushed too hard. Fronts being RFTs should not make a difference, but keep it up and you can replace all 4 at the same time next.

Been a long time since I ran the Conti's on my old e38, so can't speak to the lane drifting

[Asbjorn]

Just turn DSC=Off. Problem solved. No more freaking out. I promise.

On a more serious note, try and check your rear tire pressure. You are running non-RFT now right? Then you don't want to be running rft pressure as stated on the tire label inside the door anymore. Lower pressure should increase grip.

The lane drifting I never heard of though...

[STR3T]

Definitely something wrong. Rainy today so left it at home. I've put about 200miles on the rears now but last night coming home, average cornering at recommended speed induced same DSC/halting.

Searching around, tire manufacurers do recommend a break in period of 300 to 500 miles for new tires (performance) to ensure mold compounds, etc are out and you are getting best grip.

I've never experienced this before and lack of responses here indicate most of on here have not either.

I'm not convinced this is the actual issue I'm experiencing. I'll likely drop it off at the tire center tomorrow and have them check it out.

It's an interesting thought to just turn DTC off, Asbjorn, but I'd want a wide open lot to test that theory out beforehand given what I've seen and felt out of the vehicle this week

[CedarZ4]

Lane drifting has been a reported, albeit rare, issue with the Continental DWS that I've read about.

Additionally, lane drifting could be due to difference in tread pattern between your F and Rs.

[jparnes1]

All bets are off until you have 4 matching tires.

[STR3T]

Originally Posted by CedarZ4

Lane drifting has been a reported, albeit rare, issue with the Continental DWS that I've read about.

Additionally, lane drifting could be due to difference in tread pattern between your F and Rs.

Yeah, I'm really leaning toward this issue being due to the two vastly different tire/tread types and depths. So I might as well plunk two new DWS on front and see if it gets sorted out.

I know on my Touareg, with 4x4, you really have to replace all tires at once and of same make or at least all need to fall within a pretty tight tread depth tolerance and make or you face this kind of issue.

I did not expect this on the rear wheel drive Zed and specifically asked a number of shops if they thought this would be a problem. My guess is, if I had put the same RFT's on the rears, it would've been largely a non-issue.

[CedarZ4]

Originally Posted by STR3T

I know on my Touareg, with 4x4, you really have to replace all tires at once and of same make or at least all need to fall within a pretty tight tread depth tolerance and make or you face this kind of issue.

I did not expect this on the rear wheel drive Zed and specifically asked a number of shops if they thought this would be a problem. My guess is, if I had put the same RFT's on the rears, it would've been largely a non-issue.

The tolerance you are speaking of is only in regards to protecting the drivetrain, as vehicles with AWD will be able to sense the overall tire circumference difference (due to different tread depth) and think the car is slipping due to uneven rotation rates of the wheel. This results in premature wear and tear. So for AWD vehicles, all 4 tires must be replaced at the same time to match tread depth.

The garage that installed your wheel was correct in that in a RWD car, you only have to replace the 2 rear wheels at the same time, and having mismatched fronts will not cause a "problem" to the car. However, tread pattern difference can and does lead to drifting. This isn't a problem with the car itself, though, so this may be what the mechanics were referring to.

[nicknaz]

Originally Posted by jparnes1

All bets are off until you have 4 matching tires.

+1