I would say tires, my RWD would skip in turns on rough pavement with the stock run flats. The car rides and handles so much better since I got rid of those tires


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Ditto the tires. I had the exact complaint with mine, and it went away with a change to non runflat snow tires.
How sad is it that Blizzak WS80's are smoother, better handling, and even quieter than the OEM Michelin runflats that only had 24,000 mi on them?

 

Rudy, the Blizzak WS80's are far superior to the OE Bridgestone RFT on my CTS too. My first drive on the snows reminded me a little of a Cadillac. My tire person advised to use the RFT until it's time for replacement. He will do standard tires for me at that time. His #1 tech teases that I will use my brain next time. Lol

 

Like others said, the runflats are the likely culprit. Our ATS started doing this around 20,000 miles on the factory runflats. The Conti DWS 06 non-runflats fixed that problem - and provided a much smoother and quieter ride. Pez.

 

Another vote for tires. Mine stopped doing that after I got non-RF tires.

 

Your title, “Cause of sideways hop on bumpy curves?”, contains the word bumpy, but “bumpy” or “bumps” is not in the text of your posting and is missing in all replies.

If the roadway is “bumpy” and you enter a curve, your car will tend to hop sideways as the tires lose firm contact and centrifugal forces push outwards.

What mitigates this sideways hopping?

• Tires with good grip (as others mention here).
• Properly setup anti-sway bars
• A well-tuned suspension (springs, shocks, alignment, etc.)

 

Because of the stiffer sidewall needed to provide the run flat capability, run flat tires behave somewhat like regular tires that are over-inflated when going over bumps or rumble strips in a turn.

The higher performance ZP tires like the high performance Michelin models use asymetric sidewall stiffening inserts (these provide for the runflat capability) and the inner sidewall has much more rigid stiffeners while the outer sidewall can flex more which helps to keep the tread planted during high G turns. Standard ZP tires will have equally (and very) stiff inner and outer sidewalls and are very prone to skipping and jumping when they get upset by road features during a turn.

 

Thanks for the replies, and thanks to all who figured out my question even though I skipped the word “bump” in the body of my post (I can see exactly where I left that word out, my mess up). Looks like another drawback to chalk up to RF’s. The car only had 6500 miles when I got it & I know who drove it before me, so I doubt it’s a suspension problem - although anything is possible since it has some other pure “widget” issues I’m taking it in for next week (diff leak, CUE, headlight high beam shutter sticking), so I’ll mention the skitter to the dealer just in case.

 

I have the Blizzak WS80's and agree with you 100%. Runflats suck in many ways.

 

Shock valving has a big impact on bump steer/hop. On a RWD car, if the rear shocks allow the tires to loose contact with the road or unload the weight when hitting a bump in a curve, the back end wants to continue straight even though the front wheels are following the curve of the road. If the weight unloads, the less grippy the tire, the easier it is for the tire to break free.

I'd guess if the AWD is rear biased in power distribution, you get the same effect.