YENPINGW

Recently, I have changed my wheels from stock 17" to 18" with tire sizes of 235/40/R18 abd 265/35/R18. I just start to notice that some slight shaking on my steering wheel on some of roads. I don't see or feel the shacking if I have my hands on steering wheel. But I do see the slight shacking of the steering wheel if I have my hands off the steering wheel. However, I don't see any shaking, even when my hands are off the steering wheel, on some flat and smooth roads. Is this normal for 18" wheels??? Is that just normal road feel from the 18" tires??? Or Something is wrong ??? Any suggestions or experiences ??? Please advisde, Thank you very much.

YENPINGW

Btw, what should be my tire pressures at for my tires on the CLK430?? Please advise, thank you.

SteveChod

I put 19s on my car. It is important to have the tires perfectly balanced. First I recommend that when buying a set of tires always try to get a matched set from the factory. In your case they most likely don't offer the offset of your fronts and rears as a matched set, but you could at least match the fronts and match the rears. Then you should try to have them road force balanced. They can then tell you what your road force is on each tire. My guess is that one of your tires isn't perfect. If you go about 100mph in your car does it ride with no vibration?

YENPINGW

Thank you for your reply. I hardly go up to100mph, I think there might be my small vibration when I am at high spped. I can easily see my passenger seat is slightly shaking when no one sits on it. I think my front tire pressure is not correct. It's a little deflation. Any way to resolve that sort of problem????

SteveChod

What are you running your tire pressure at right now in the front and rear?

mmgrad

lets see... for stock 17s, i suggest 38 front/35 rear... this will correct the underinflation problem up front.

when i had my 19s, i had it at approx the same setting. don't use the setting on the fuel panel

you can up the psi a little more to protect those 18s and 19s from pot holes, but you get a slightly more harsh ride... i think 38f/35r is good.

LowRydeR

You might need hubcentric rings.

-Bruce

SteveChod

That sounds a little high? Do you really run 38 front and 35 rear? I thought it was suppose to be lower? How can you figure this out?

Steve

YENPINGW

Hey guys,
Thanks for all your reply. I think the shop who mounted my wheels did put the hubcentric rings on the wheels...As far as the tire pressure goes...I don't know yet..I have Pirrelli P7000 tires and it states that do not exceed 51 psi. One of my friends sugeests me to have 45 psi on them. I don't know if that is too much. That is why I am trying to find out what you guys have been running......Thanks

mmgrad

running it at 33psi (based on the fuel flap) will cause the fronts to be extremely under-inflated due to the added weight of the V8 engines. therefore, the tires will experience extreme pre-mature camber wear on both the inside & outside of the sidewalls.

running it at 38psi will correct that problem. the ride won't be as comfy, but you won't really notice much. MB keeps it at 33psi to maintain a luxurious comfort level, but it eats away the tires real fast.

mmgrad

if you are running 19's, you can safely go 40psi up front, and probably 37/38 in back. this high of a psi will help prevent damage from potholes.

remember that for every 10 degrees of heat build up, the psi goes up about 1 also... so you don't want to overinflate it.

45psi is a little high for my taste. I would keep it at 40 or below. just my thought

YENPINGW

Thanks a lot, Danny.
I have adjusted my tire pressure to 40psi front and 38 rear. Hopefully, that will make it better. As for as the slight shaking goes, is that what you suppose to expect from the low profile tires???

mmgrad

I just re-read the post about the shaking... if you are just referring to the passenger seat shaking, i think that is 'fairly' normal...

the question is do "you" feel the vibrations? if so, then you might want to have your wheels re-balanced, or some other forum members have noticed that its the tires, and the problem went away when they changed to different tires.

also, make sure when you changed to 19s, that you got the appropriate sized bolts too.

SteveChod

Interesting!..Maybe I was underinflating them. I will add some more air in mine and see how it rides!

YENPINGW

Thanks, Danny.
As I was driving today, it feels much better now. I am still having the small vibration on my steering wheel sometimes. Most of the times, it happens when I am on the freeways. You know how some of the southern california's freeways are. It doesn't have the small vibration when I am on a nice and smooth road though. But it's there when the car is driven on rough roads, hopefully, that is just the road feel. Is that something I should concern about???

mmgrad

Yeah, i know how the LA freeways can be... although it doesn't seem as bad as how some people describe NY streets... but anyways, a rough ride can be normal depending on the road.

But, your steering wheel should not vibrate. If the vibration occurs during braking, then your rotors are warped and need to be replaced. Try and observe when it vibrates, and take note of the road conditions at those times... see if any patterns develop.

Any vibration should be of concern, but I wouldn't worry too much unless its becomes very noticeable.