This is on a non MB, but the other sites that I frequent just don't have the savvy members and sponsors that are at mshop.

I took off a set of 15" 65 series Continentals and replaced them with 40 series 17" Kumho Ecsta ASX. I read reviews on this tire and a few people said that it had too much squirm. Being the rookie when it comes to ultra low profile tires, I figured that "how can they possibly have more squirm than 65's? Well, believe me, they do. I was amazed.

Before changing tires I had changed to a stiffer rear sway bar and absolutely neutralized the handling of this little car. It was amazing and a total hoot to drive.

Two questions; (1) the squirm seems to offer an understeer effect. Would stiffening the rear sway bar (it is adjustable) eliminate some of this effect? (2) Would increasing pressure eliminate a significant amount of squirm and if so would there be tire wear or other problems associated with this?

I can probably learn the answers with experimentation, but I would like to hear your responses whether based on theory or experience.

BTW, I was also totally amazed at the fact that these tires, that look like a thick rubber band stretched around a wheel, gave a ride just as soft as the 65's.

Thanks,

but often, what you have is a case of very soft sticky rubber combined with a deep enough tread pattern to make it last a few thousand miles, and the result is a very high limit of adhesion but a lot of slip angle long before that limit is reached, and also a bit of squirminess even in straight-line conditions. Such tires generally improve a lot as they get half worn out, and that often doesn't take long, but it's not a great consolation when they're new.

You can try increasing the pressure by a serious amount, but that will also shorten tire life somewhat in many cases (not always). Preloading the sidewalls and rubber with a bit of extra toe-in also sometimes helps, again, at the expense of more rapid wear. This sort of problem is often very individualized amongcombinations of brands of tires and models of cars.

Fimum Fit,

Thanks for your response. I have had new, deep tread tires do this before, but I had forgotten about it. Thanks for getting me back to Earth.

These tires are 30,000 mile guarantee tires with a 420 treadwear number. I don't drive this car a lot, so this is probably several years worth of tire.

I have an adjustable rear sway bar on this car, so I can easily stiffen it up. If I do tighten it up, do you think it will compensate at all?

Thanks again,

It would increase the weight transfer at the back end and therefore keep the front weight more evenly divided between the front tires, which reduces understeer in steady-state cornering conditions, but I don't think squirm is a steady-state phenomenon, but a transitional behavior, so it shouldn't be affected much. I'd try to reduce the sidewall flex component with a little more tire pressure first.

Sorry to end the discussion, but I'm headed for a couple of weeks of family reunioning in Minnesota early tomorrow morning, so I probably won't be able to access any of my favorite sites more than once or twice until it's almost August.

it sounds like you are experiencing tread squirm which all tires have. The taller the tread block the more it will flex causing the sensation you are describing. Air pressure adjustment and a little tire wear would be the best way to reduce the squirm you are feeling

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