valeoray

I'd like to ask he suspension experts on what the difference is in specs between the cars my family owns. I have a 2011 IS250 AWD and my wife has a 2013 C300 4matic.

Her wheel gap is less than mine, and her ride is much more comfortable in terms of dampening when going over manhole covers. This is comparing her stock 225/45R17 inch continental tires (all seasons or winters; doesn't matter which) to my 16" winter Hankooks. The 16" are already softer and more comfortable than my 17" OEM Bridgestones (which are a bit worn), but I still feel the shock when going over manhole covers; more than the Benz.

I'm a NOOB in terms of struts/shocks/suspension. I kind of know about spring rates. Any insight would be appreciated. Thanks!

FSportIS

iTrader: (13)

A stock Lexus IS250 feels super comfortable, actually way too soft for my taste. I think the feel is very subjective as it is hard to describe technically what is more comfortable. What is comfortable to one person might be super stiff for someone else. It is all your perception and how you feel.

Also, I want to point out that comfort and handling performance do not go hand in hand. Generally speaking (don't quote me on this), good handling performance will inherit some kind of stiffness (high spring rate, stiffer dampening) in there to reduce body roll during cornering.

knguyenk

I was also surprised how comfortably the C230 rode when compared to my once stock IS 250 AWD when I had a chance to drive it before it was totaled when someone T-boned it (another story). The MB was also fitted with Continentals, ContiProContacts I recall, where my car was fitted with stiff, loud Goodyear Eagle GTs.

I've read somewhere on the forums that the larger gap on the AWDs were to allow for the driver to install snow chains with ease, it's not for suspension travel from my understanding.

I've also noticed that the 250 AWD is rather stiff when comparing it to its RWD counterpart and I cannot really explain why either since the weight difference between the drivetrains with the same engine is roughly about 200 lbs and messing with the tire pressures can get the cars to ride rather comfortably. This means that the spring rates are (probably) the same; so this only points the finger to either the added components of the AWD which requires completely different shocks for AWD and RWD (but springs are interchangeable). However, that is just my assumption based on my knowledge of automotive suspension and the differences between the 2IS RWD and AWD layouts.

As FSportIS mentioned:

To expand on the comfort versus handling compromise (for FSportIS), I've read and seen a test where a S2000 lap time was compared with its stock 17's and the newer generation's 18's and found that the 18's were quicker, easier to turn into the corners but the ride suffered slightly with the smaller sidewalls that transferred the bumps to the driver.

Incidentally, Sewell makes a similar comment with the handling and comfort in their forged F-Sport wheels (the last sentence of the first paragraph in the description).