Car feels like it's floating after new tire install

[Dsmith408]

Afternoon Gents,

I'm a newb when it comes to wheel and tire combinations, so excuse my ignorance but I don't understand my issue. My car is lowered on Sportline springs and wheel spacers. I just installed some fresh 255/45 r18 continental extreme contact tires on an 18'' Rim. After searching many opinions the conclusion was this tire size is not an issue at all for this rim size. Upon taking the car home, with the pressure at 35PSI, the car literally was floating back and forth on the road, the steering wheel felt slightly shakey. The car got adjusted to the max PSI at 51, but the issue remained. I tried to explain that didn't feel like the issue at all.

1 ford dealership told me it was my '' electrical steering system ''. However, after being fed up with that ford dealer, it got transferred to another one 10 miles down the road. Only to have the service guy there tell me that the previous tech came up with his conclusion on a forum site. Was pretty blown away by that. None the less, I don't know how to tell these guys how to do their job, so here I'm for more opinions on what it may be. Has anyone experienced this?

Thanks -

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[NightmareMoon]

First off, what wheels & tires are you coming from?

 

[Dsmith408]

First off, what wheels & tires are you coming from?

coming from the Stock 18'' Rims and the stock Pirelli 235/50/18

 

[NightmareMoon]

Ok, so similar profile tires and 18" diameter is what I was curious about.

I think you're just experiencing the full squirmy tread depth of brand new tires. Old tires with worn down treads and new soft tires with full height tread blocks have a remarkably different feel, with new tires being uncomfortably squirmey feeling at first. Even tho it feels like night and day, its normal. Aside from the tread blocks, old tire rubber is rock hard compared to new soft tire rubber and that also contributes to the remarkable change in feel. Yup it feels worse, but the contrasting feel will go away quickly as you get used to it.

That, and the continentals are known to have kind of soft sidewalls.

 

[Dsmith408]

Ok, so similar profile tires and 18" diameter is what I was curious about.

I think you're just experiencing the full squirmy tread depth of brand new tires. Old tires with worn down treads and new soft tires with full height tread blocks have a remarkably different feel, with new tires being uncomfortably squirmey feeling at first. Even tho it feels like night and day, its normal. Aside from the tread blocks, old tire rubber is rock hard compared to new soft tire rubber and that also contributes to the remarkable change in feel. Yup it feels worse, but the contrasting feel will go away quickly as you get used to it.

That, and the continentals are known to have kind of soft sidewalls.

Makes all the sense in the world. I had a feeling this might've been the issue. Can you elaborate on '' soft side walls '' and why this makes a difference? In light of what you said, I feel bad a little then because I really got into the manager at ford over here, lol.

 

[NightmareMoon]

Makes all the sense in the world. I had a feeling this might've been the issue. Can you elaborate on '' soft side walls '' and why this makes a difference? In light of what you said, I feel bad a little then because I really got into the manager at ford over here, lol.

Soft sidewalls flex more, which can allow a tire to move a little more under different lateral loads. Also helps them ride comfortably and may help them grip a bit. You might catch mention of it in professional comparison test reviews of the tire.

I’ve never driven on the Contis personally but I’ve hear the soft sidewall mention a couple of times. chances are you’re feeling mostly the change from old to new rubber and the taller tread blocks.

FWIW, I'd probably run normal pressures (32psi cold). Run pressure too high and the tires will wear out the middle of the tread a little early in their life.

Good lesson tho in maybe not jumping to conclusions tho and tearing into somebody without triple checking your facts. We’ve all done it at some point. I gave an alignment guy a real hard time once for messing up my clutch, and later learned my clutch pedal kind of does that on it’s own. Whoops. Guy probably thought I was off my meds.

 

[Matti777]

' floating back and forth on the road, the steering wheel felt slightly shakey. ' sounds more like an alignment and/or wheel balance issue. I would start with the basics and get both checked again at a good tire shop. The last time a Ford dealership did tires for me they mounted the tires backwards.

 

[Exhausted]

I read about this as I just went to nitto nt555g2 and it turned out to be the stuff used to release the tire from the mold machine.
About 200 miles in and it’s gone
I read it can take up to 500 miles

 

[NightmareMoon]

I read about this as I just went to nitto nt555g2 and it turned out to be the stuff used to release the tire from the mold machine.
About 200 miles in and it’s gone
I read it can take up to 500 miles

also a very good point. All bets are off until they scrub in.

 

[Dsmith408]

Good lesson tho in maybe not jumping to conclusions tho and tearing into somebody without triple checking your facts. We’ve all done it at some point. I gave an alignment guy a real hard time once for messing up my clutch, and later learned my clutch pedal kind of does that on it’s own. Whoops. Guy probably thought I was off my meds.[/QUOTE]

LOL! Well said, and agreed. Appreciate the insight.

 

[Zathras]

I dunno if it's your issue, but in general wider tires tend to tramline more (wander, follow ruts in the road, etc.)

Also, with a wider tire on the same wheel, the sidewall may have more curve or flex to it.

 

[GT 550]

Might be worth dropping the pressure back to stock or 2-3 psi over first, not sure what max hot pressure is on the Contis (it's written on the side) but IMHO 51 cold is over the top for normal use, the tires will be riding on the middle section of the tread.

Drive for 100 miles or so to scrub the tyres, as suggested the release compound can make them feel greasy assuming the shop didn't remove it as they often do for motorcycle tires.

In the interim if the steering wheel is shaking/vibrating consistently on a flat road at 60mph it's probably wheel balance. Ask them to redo and rotate the tire on the rim so they use minimal added weight to get the balance right. Then if the problem persists and you got it aligned there ask them to check it or go elsewhere.

 

[BillyJRacing]

ExtremeContact SPORT tires?

 

[Dsmith408]

ExtremeContact SPORT tires?

Yeah, they're the Extreme Contact SPORT tires.

 

[Flimflamman]

Sounds like a good ole tire roast is in order. Roast them, rotate front to rear, roast again. You're all set!

I'll show myself out...

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