Unsolvable mystery, steering jerks left/right on irregular road on new wheels, old wheels drive fine

Hopefully anyone can help.

Currently driving on 17 inch rims but I have some 18s that I purchased used. I had it wrapped in brand new michelin a/s 4 tires and thats where the problems begin.

The steering jerks left and right when driving on bumpy roads to a point where I feel very unsafe. I essentially have to grip the steering wheel tightly with both hands so I dont veer into another lane. Not only does it jerk, it feels as if the steering becomes disengaged with the tires and the steering wheel becomes very light and loose. On smooth roads, it drives fine.

After trying many suggestions from other users and failing to resolve this issue (3 tire balances, 2 alignments, front and rear suspension replaced) I finally decide to put back on my 17’s and low and behold, the problem disappears.

The issue seems to be the tires or rims, but all the tire guys have said the wheels are not bent and the tires are good.

What do you think may be causing this issue?

Specifics:
-car is not lowered (edit 7/12/2021, car is “kind of” lowered, I replaced the stock suspension with an OEM honda HFP (sport) suspension. Car rides stiffer and lowered by just 1/2 an inch)
-Both the 17’s and 18’s are OEM honda wheels
-17’s are 17x7 (P215/45R17) and 18’s are 18x7 (P225/40R18)
-the 18’s were made for the same car model but on a higher sport trim level, according to honda, upsizing wheels should not be an issue and is within spec. Wheel geometry should not be an issue
-I am not using wheel spacers
-Hub was cleaned with steel wire bush and sits flush with wheel. I did not check the 18’s wheel bore so I will give it a thorough check as well. As far as I could tell, it is clean.

Tire pressure.

What year make and model Honda is it?

Your suspension does not have stiff enough springs, strut mounts and firm enough struts to control those heavier, stiffer, low profile tires. This is a common problem when a performance wheel and tire is installed on the “non sport” version of a car even if they came on the sport version. There is a lot more to the sport version than just bigger wheels and tires. That is what is causing your problem.

I used to “tune” these systems as part of my job with a major automaker, so I am familiar with the problem.

Change back to the 17s.

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You changed suspension. With Oem “sport” struts and springs?

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Do the new rims have the same offset as the 17s? Probably do, but worth checking. I’m surprised such a small change in rim size/tire profile would do this.

What year/miles?

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also low profile tires dont absorb as much of the road shock as regular tires because there is less side wall.

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Hey Mustangman,

Sorry I left one part out on my original post. I had switched out my front and rear suspension with an OEM honda HFP (sport) suspension rather than the base model one.

It does not really lower the car (maybe just 1/2 an inch) but the stiffness should be a lot more.

My car is a 2014 civic lx and the suspension belonged to a 2012 civic SI HFP model.

I had said “my car is not lowered” since I didnt want any confusion that my jerking steering could be due to a lowered car. I was experiencing this issue even before the Sport / HFP suspension install.

Do you think it may any suspension component that I did not upgrade that may be causing this issue?

Thank you Capriracer, The tire shop did indeed ove inflate the tire to 34 psi but I dropped it back down to 32 and am still experience this jerk.

Car is a 2014 civic lx automatic

Correct. My car is a base model civic but switched to the SI HFP suspension setup

Hey Texases, I am not sure of an offset difference but I will check. This would affect the jerkiness of the steering wheel?

My car is a 2014 civic lx at 90k miles.

Can you return the new 18" wheels, or otherwise get your money back?

I would imagine you’re stuck with the tires…but I think any solution other than putting the 17s back on is going to be both time consuming and expensive.

A lot of times, it seems like these “upgrades” really only benefit the people selling the “upgrades”…

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The new ones are a factory size wheel, not even the largest ones. One difference, the 18" tires are one size larger than factory, 225/40 instead of 215/40 x 18. Wonder if that makes enough of a difference?

I think @Mustangman summarized it very nicely above.

I had my own lesson in stupidity, where getting from 16-inch wheels to 17-inch wheels resulted in a similar, although lesser pronounced impact on drive-ability, where I bought winter tires with nice alloy wheels on a closeout, while matching width, rotations per mile and hub offset… still, it was not exactly pleasant to drive the thing which wanted to whir out of proper trajectory on any bump. Luckily enough for me, I was able to sell full set almost for the same money I paid.

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Well, suspension is springs, struts, control arm bushing hardness, sway bar diameter. Sway bar bushing hardness. I changing my civic lx tires from 195/60/15 to 205/55/16. Both were steel wheels. I know a larger dia rim will weigh more then a smaller rim. Steel or alum. I think the car seemed more stable with the 16” wheels.

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Agree with @Cavell … Just how much of “the suspension” did you change?

Dropping from 45 to 40 series alone will make the car "dance’ a bit on bumpy roads… after all the car is prelty small and light. The tires are 2 lbs heavier, each. depending on the wheels I looked at on TireRack, the difference between 17s and 18s was 2 to 4.5 lbs… sooo you are putting 4 to 6.5 more unsprung lbs on each corner of a 2750 lb (plus you) car. That is a big add.

Plus you put a 2012 suspension package on a 2014 car not knowing what changed between the two model years. It was an experiment that didn’t turn out so well. I’d sell the 18’s with the tires and all and put the 17s back on. You didn’t gain anything but the looks and lost the ride and handling.

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Beyond the good ideas above, it sort of sounds like an alignment problem, esp the toe settings. It’s possible the toe was incorrect before, but didn’t show up as a symptom b/c the 17 inch wheels are less sensitive to incorrect toe for some reason. I’m guessing there’s not enough toe; i.e. the wheels are pointing too much straight ahead. Common sense says to inspect the wheel bearings, suspension, and steering system bushings for too much play before embarking on an alignment. Did you have any weird wear patterns on your old tires?

Damn… the truth hurts but you are the man

Really appreciate your time and advise. :pray:

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