Keithb

so, my P zeros were bald and I decided to put on some Conti Extreme DW in 265/35/18 on the rear. Fronts are still P Zero stock size.

At the same time got the alignment done to take toe in out of the rear. Original reat toe was ~.45/.45 camber was -1.5. Left the camber and we changed the toe to .21/.21 (R/L). Front alignment was pretty much bang on so we didn't change much there.

I went with the Conti's as they seemed to get much better reviews than the Hancook Ventus (which I have on my C320 coupe) and were about $80 per tire less than the PSS. Seems like a good combination, so I thought I'd give them a try.

Went for a 20 km drive which includes one of my fave 5 km twisties. On the straights, everything seemed pretty good. Car felt like it was pretty tight, even with a bit of left/right movement on the straights (just warmin up the tires ). Hot pressures were 43-44 all around.

Once I hit the twisties tho, things got a little different. Seems like either the tires or the alignment has brought in a bit of understeer in cornering. On tighter turns with a bit of a late "snap" / turn in to the wheel it almost felt like a "bounce" then turn with a little understeer. Did it about 12 times just to make sure it wasn't just a bump or something else. Other than that, things seemed to work well, once I mentally allowed for the little bit of understeer, the car was turning very nicely.

Question: Do you think it's the alignment that makes the understeer seem more prominent, or are the sidewalls of the Conti's just softer than the P Zeros?

m a x i m u s

I would think taking some rear toe out of the car would create some understeer, but it may also be a combination of that with brand new rears, which may produce more rear end grip than your old tires. Maybe put the toe back to the way it was and then test it again.

bmwcousins

Any noticable difference in high speed stability?

Keithb

Not in the short time I had it up to 130 kms. I'll be doing a 250km hiway drive Monday, so that should be interesting to see how things handle on the hiway.

@maximus - the whole point was to take a bunch of toe out to (hopefully) get more than 8000 kms out of a set of rears.

bmwcousins

If you don't mind, let us know how that works.
I put a ton of highway miles and a few extra per set would be a good thing.

Thanks

Merc63

I put my rear toe to just about the same as you. I haven't noticed much of a difference in regards to drive feel. Tires seem to be lasting longer though, which is why I did it.

Velociabstract

Removing toe in out back frees up the rear of the car. My guess is different brands front to rear with different grip profiles, or the rubber is too new. The lubricant they use in the mold to make the tires pop out easier requires a few hundred miles to rub off. Report back after a few hundred miles.

Les

derspi

Dialing out rear toe-in promotes less stability so getting more understeer is exactly the opposite of what should be happening. It probably has more to do with the fact that you have more grip in the back than you've had in a while (balding rears that were a tad narrower) and little to do with the new alignment.

Keithb

@bmwcousins: I put 250 kms on the hiway this morning and the car was perfect. The conti's might have a little less stiffness in the sidewall - I've driven the same road every week for the last 2+ years and realized the bumps didn't feel quite as hard. Overall, hiway drive was really good with the conti's on the back.

@derspi: I think you might be right. I think what I'm thinking is understeer is really just a bit of body roll as I snap the wheel on a late turn in. The fronts grip and turn, and the rear just grips and follows around with a wee bit of body roll. I'm guessing with the bald pzeros I was just sliding a little and didn't really notice. Interestingly enough, the ESP light hasn't gone off yet since putting the new rears on.

Keithb

As a follow up to this, I took the summer wheels off the car on the weekend and here's the details:

I had the rear alignment changed to the toe to .21/.21 (R/L) when they were installed.
I put 6900 kms on the tires from date of installation.
The wear on the Contis is hardly visible, the tires look new still.
I had put about the same # of kms on the P zeros (well 8,000kms) with toe set at .45 and they were toast.

ShaneN.

I'm not familiar with the original tires you had, were they run flats? And are the new ones? When I had my c6 i went from the stock goodyear runflats on the front of the car to something that wasn't funflat and clearly a softer sidewall and it was actually a little scary at times. i had a lot of confidence throwing the thing in the corner with the runflats but after the new tires it almost felt like they were folding over, even though i knew just the little bit of feeling was making my mind exaggerate what was actually happening. however, you just changed the back ones so i'd wonder if that was more the alignment.

ShaneN.

oops, guess i should have kept reading. well, good results.

gthal

It could be as simple as running different tires front/rear. PZeros in the front and Contis in the rear won't be good for balance... normal driving probably unnoticeable but aggressive driving it very well could be. That couldd be what you are feeling.

m a x i m u s

Nice testing. I'd say your toe adjustment helped with tire wear.