My 07 MCS has a little under 9k miles on the odometer. Last week I replaced my two front Dunlop runflats with Conti runflats. The new Contis are now on the back, the still-usable Dunlops on the front.

My daily commute is 75% fun (windy mountain road), 25% boring (city streets). The former accounts for the rapid tire wear.

This morning, on my way to work, the DSC kicked in several times when going around corners. I was not going very fast so it struck me as very odd.

I’m thinking the mix of two kinds of tires is causing the DSC to be confused.

In comparison, the DSC in my 03 MC only kicked in a few times over the 45k miles I drove it, and it was always when I was going around a curve at high speed.


The tires are all at 38 psi. I checked the air pressures when I got home from the tire store (Americas Tire) and was surprised to find they did not inflate the tires to 38, as I asked. Three were at 33, and one of the new tires was 31. Oh, and two of the lug covers were also loose. I guess $525 isn’t enough for the tire store to do a good job :-(

 

i've never been to a shop/dealer that inflated tire pressure as i request, always have to adjust it on my own

on my r53, dsc only kicks in *after* wheel spin occurred. sometimes it's very slight wheel spin, but i've never had it when it kicks in w/o me noticing/anticipating. however, my tpms has gone off when tire pressures are off on the same axle. happened after a dealer balancing and mismatched my tires, since i inflate the fronts and backs differently. maybe that's what's causing it?

 

new tires are slippery until broken in. could be that.

 

> new tires are slippery until broken in. could be that.

Oh yes, thanks for the reminder. I should know this; I was always really careful after getting new tires on my motorcycle, knowing they needed breaking in.

 

Go to each of the tire manufacturer's websites and look up the both tires. Compare the overall diameters and/or revolutions/mile. My guess is that they are a bit different.

The traction control (part of the DSC) works by comparing the speed of each wheel in relation to the others. If one wheel is spinning faster than the others, it engages the traction control, cutting power or applying the brakes to that wheel(s). The computer allows for a only a certain amount of variation, a bit of slip, before it engages. When using tires of different diameters, the computer sees a variation in speeds all the time. That cuts into the slip allowed by the computer, so the traction control kicks in sooner.

I don't understand BMW's assertion that the tires shouldn't be rotated. Rotating your tires is the best way to get the most out of the whole set. Besides, it halves the number of times you have to have to deal with the yahoos at the tire store!

-Will

 

The point about tire diameter is interesting, but what about the fact that, prior to replacing them, the front pair was almost bald whereas the rears look good as new. There is surely a large front-to-rear diameter difference, yet no DSC kick in.

 

You need to rotate your tires more often. They should all wear out at about the same time.

Probably has to do with still having some mold release on the tires, but you can quickly check the tire dia. at TireRack.com.

Did you reset the tire pressure sensor system? I wonder if DSC gets its info from there? I would think it would need that data.

Interesting point about dia. change with wear. I wonder if the system adjusts for slow changes? If it is sensitive enough to notice that dia. change, it would need some way to adjust.

 

Yeah, that point hadn't escaped me, I don't know how manufacturers calculate rev/mile. Your typical tire only has a tread depth of 10/32", or a little over 0.3 inches. For the overall diameter of the tire it's a difference of 836rev/mile new and 848rev/mile bald for the Dunlop SP SPORT 9000 DSST in a 205/45/R17. For a Continental ContiProContact in the same size TireRack lists 856rev/mile. Is that going to give the DSC fits? Honestly, I think not. I partially rescind my previous post, as long as you are using the same size tires front and back.

It is entirely possible that the system notices the static difference in the wheel speed front to back and "zeros" itself during a diagnostic cycle each time the car is started as Robin suggests. Why not, right? However there's very little reason why it should need to.

I suggest you turn off the DSC and do big smoky burnouts until the older Dunlops are completely bald. Next do some fast driving to validate that this worsens the DSC issue. Then it'll be time for a new pair of Conti's on the front. Get new tires and report back with your findings. Videos of the burnouts are key to determining root cause.