calvin2376

iTrader: (2)

I just bought my IS350 2 weeks ago and love it, but I wanted to ask if anyone else has experienced what I am. It seems that the car is extremely sensitive to road undulations and the steering wheel will swerve severely when running over undulating roads. I'm not talking about potholes/road joints, etc, but more just roads that aren't perfectly smooth, may be on a sideways incline or decline, or have up and down undulations.

When I go over these, it seems the car swerves severely in response. I'd be driving down the road and not even see a particular undulation and as I go over it my steering wheel would swerve to the right or left. It doesn't seem to be an alignment or balance issue, since both were just performed two weeks ago, it runs straight on smooth roads, and there are no other symptoms. It just seems to be a feature (bug) of the car.

My previous car was a 2003 E55 AMG which had stiffer suspension and heavier steering, so it could just be I'm not used to a smaller, lighter car with lighter steering, but on the exact same roads the AMG never swerved like the IS does. I saw another post about a swerve above a certain mph, but this issue happens at any speed (and is actually worse when going slower).

Anyone else experience this or have an explanation?

Lexitegra

iTrader: (2)

It might be your tires. When I purchased my vehicle, the previous owner had 3 different tires on it (all with different tread-wear, 1 rotational installed backwards actually) and I did kind of experience what you're describing. I'm not saying you have 3 diff tires, but it might be the tires you're driving on. Although if the steering wheel swerves severely, I'm not sure that's entirely normal.....

mslugx

you only have this car for two weeks, maybe you have bad alignments or is because the tires you have. are they low profile tires? Maybe because you get caught between tramlining. Like me, some car doesn't do that, but i notice 350 does it a lot. I had this issue last week, but it was a different issue, and older car too. What car did you come from?

CleverName

I had the same complaints with my IS. Put it on an alignment rack twice (no issues found), then took it Lexus knowing that if I didn't find an fix I was selling the car. The mechanic took me on a test ride and confirmed the problem was normal to the low profile tires (Goodyears in my case) on the 18" rims. His comments were "Drive any IS with 17's and it goes away, but this is normal with your stiff sidewalls and 18" rims." Rather than sell the Lex I gambled and bought 17's and sure enough the car drives soooooo much better....
I may research low-pro tires with softer sidewalls to use my 18" rims, but I think I prefer the added comfort of normal tires with sidewalls so will probably just stay on 17's till I decide to sell the car.

Just my 2 cents
V

dmvp29

“Low profile“ describes an especially short sidewall height, or aspect ratio, on a tire. That’s the amount of rubber between the outside edge of the wheel or rim, and the road. Shorter sidewalls provide crisper handling and positive feedback to the steering wheel, but also give a rougher ride because of less cushioning between the rim and the road, which sends each bump and road imperfection directly to the suspension. Many people also like the looks of low-profile tires.

All tires have a size code, such as P245/45ZR17, on the sidewall that displays the tire’s dimensions. The aspect ratio is the number following the slash — 45 in the aforementioned code; the smaller the number, the smaller the sidewall height.

You can find low-profile tires on sports cars as well as vehicles with large diameter wheels, such as the Cadillac Escalade with optional 22-inch wheels. Sports cars will use the smaller sidewall height for handling performance reasons, while the Cadillac’s huge tires and short sidewall allow a combined diameter that can still fit in the wheel wells.


From ask.com -->

http://ask.cars.com/2007/06/what_are_lowpro.html

dmvp29

Every where you look these days it seems you will see a certain type of tire more and more. A lot of people want a sporty, racer look to their vehicle and just the sound of the words 'low profile tires' impart sentiments of intense and speedy to mind. But do you actually know what low profile tires really are, and are they the most effective option for your particular automobile? You might just find that there's a lot more to consider in regards to your vehicle's tires than just appearance.

The low profile variety are more distinguishable than their higher counterparts, being lower and wider than high-profile tires, but the thing to remember is that when you are moving down a highway at 80 miles an hour, looks aren't as important as performance and safety. Considering the fact that all that's keeping your automobile on the road is four pieces of rubber adding up to a square approximately the size of a pizza box, good tires are a crucial consideration.

What matters in a tire is the amount of contact and grip your car has between the tire rubber and the road. Higher-profile tires have a longer and narrower contact patch with asphalt, whereas low profile tires have a contact patch that is broader, but shorter. So what does all that mean for you and your vehicle in plain English? Essentially,it means that your car will handle and perform differently on the road with these types of tires. Cars with wider tires have more cornering force, while higher tires have the distinct disadvantage of not being capable of deflecting side loads and the steering of the car is not as responsive in curves.

Another reward that comes with low profile tires, besides cornering force, is that the rubber uses less of the overall diameter of the wheel and tire, which signifies that the wheel itself can be bigger. What this means for you, as a driver is that bigger wheels means bigger brakes, and stopping ability is a crucial thing to have when you're driving fast.

Of course, as with anything there are disadvantages to installing these on your car. A vehicle that was configured with a narrower tire in mind will not be nearly as stable with low profile tires installed on it. In addition, wider tires with shorter sidewalls incline to have a rougher ride on bumps in the road, and virtually seem to look for out the worst parts of the road. A harsh ride isn't just tough on riders; it's also hard on the tires and your automobile.

Just about everyone today drives on straight highways and they don't require the additional cornering force that low profile tires provide. However, if you reside in a region that has a lot of tight turns and necessitates enhanced control, low profile tires could just be what you are looking for in tire load capacity and handling features of your vehicle. In any case it all comes down to a personal decision.

calvin2376

iTrader: (2)

Thanks for all the great info, this is very helpful. I do in fact have the 18" ISP wheels with quite low profile tires, so that's probably what's driving the experience I'm having.

willfxp

I had the same issue with my 250 with 17" wheels. My front wheel bearings were on the way out. Replaced them, and it helped a lot! The "leftovers" for me can probably be attributed to me not having low profile tire experience (my previous rides were a Jeep and full-size trucks, both with all-terrain tires).

Check this out too: http://www.tirerack.com/tires/tirete....jsp?techid=47