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Discussion Starter · #1 · (Edited)
ive been getting a vibration on my steering wheel recently so i rotated my tires front <----> rear. it was still vibrating after this. so what i did to make sure the tires are the problem i changed all my rims(225/40 r18) to my stock rims(225/45 ZR17). #1 the vibration went away and #2 very comfortable ride!

what im going to do now is change my tires on the 18" rims.

so my question is what tires do you recommend? and can i get the same comfort if i get a 225/45 ZR18????? will it even fit? in terms of the fender in turns since 45 will be bigger. if it does work it should be as comfortable like the r17's, right?

what exactly absorbs the bumpiness of the ride? the 45? or the r17?
 

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2004 C230 Kompressor Sport Coupe
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Start by getting your tire/rim combo road force balanced. Now that you know it's a tire or rim you need to find out if it is a bent wheel or a bad tire. Both with start out immediately if they are road forced balanced.

Your wheels are properly hub centric, right? If they are not you will never be able to get the vibrations out and your car will eat struts and shocks.

225/45R18 will make your car accelerate more slowly, make your odometer and speedometer wrong, and may rub. The error and acceleration difference will be about 4%. All other things being equal, taller sidewalls means a better ride. Beyond that, lots of tires get different internal designs from 40-series and below, making the ride even harsher.
 

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What brand are your 18s? Lesser quality aftermarket wheels are notorious for problems like this, hub-centric or not. So get the wheels independently checked out. If they're a lesser brand get some good ones, Tire Rack is a great place to start and ebay is a place to be avoided. ;)

After the wheels is tires: I would not exceed the proper size on the tire. I'd be shocked if you could go to that size and not rub on the front.

FWIW, here's what the tire numbers mean. And it's both in answer to your question and you'll shortly understand why.

The first number is the cross-sectional width at the tread expressed in MM, so a 245 is about ten inches wide.

The third number is the diameter of the wheel.

The middle number is the "aspect ratio", which is the height of the sidewall expressed as a percentage of the tire width. In other words, a 245/50 tire has a sidewall that is about 5" tall at proper inflation.

When you go to an 18" wheel you subtract one full inch of sidewall height so instead of spongy rubber compounds you have aluminum (or steel, eek) which doesn't absorb shock as well. That is terribly oversimplifying things, but it would take several pages to discuss the various parameters.

For more fun with tire sizes, check places like Tire size calculator and www.1010tires.com

Take care and enjoy the ride,
Greg
 

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No, that's likely to be something more serious. Check the usual: bushings, ball joints, wheel bearing, wheel bolt torque. Some of that stuff (like the ball joints) can mean a serious accident if it fails while driving, so don't delay.
 
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