RotoRocket

iTrader: (1)

As most know, my 8 has been fantastic.

I just had new summer tires put on (BF Goodrich g-force sports) that are the same rating/size as the OEM summer tires.

The tires are actually better than I expected.

Here's where it gets odd.

I started noticing a jouncy ride with a body shimmy at speeds over 70 mph on concrete sections of highway after getting the new tires mounted.

When I say 'jouncy' I mean that there is excess travel up and down, and not laterally, and when I say 'shimmy', I am talking about a very odd feeling of the car moving ever so slightly laterally as if side to side, emanating from seems like the rear, and in a consistent pattern. The body is still taught and rigid, but there's almost a swaying at higher speeds.

This was not present in any form with either the OEM tires or my winter tires (iPikes), but only manifested itself immediately after getting the new tires mounted.

So, I went back to the tire place, and they put all 4 wheels on the balancer, and sure enough, there was one wheel at the rear that was out of spec by .48.

The guy tells me that he can't get it to zero, but that he can get it well under .25, and that within this parameter (anything under .25) the problem should go away.

He tells me that he doesn't have a more sophisticated machine like a higher end roadforce that could do more precise analysis, nor does he have wheel weights as small as 1/4 of an ounce, but will make it right.

I ask him if there's any damage to the wheel itself, and he says no and that it's true as can be.

So, he does a good job and gets it to balanced pretty well (I think it's about .17), and tells me if there's any problem, it will now manifest itself as vibration through the steering wheel, because they rotated the tires just to be thorough, but he doubts there will be any problem.

I thank him and take it out on the highway immediately and run it up to the 75mph+ area where there's clear highway, and it's vastly improved, without any vibration through the steering wheel.

This make me pleased.

My questions, for those who might know the answers, or who feel like taking a SWAG, are:

1) Is this common when getting new tires replaced?

2) How close to zero can one reasonably expect to get on a vehicle that's literally in like new condition, and tracks straight and true in terms of alignment, without any damaged wheels, and that's never been in any accidents?

3) Is this going to pose any problems 6 months, a year, or longer down the line, or re-appear as a problem?

Thanks.


*Mods, if you feel the need to move this to subsection, no contesto, but I get more feedback when I post in the Main Forum*

godesshunter

I work at a tire shop and see this every day... 0.00 balance is completely unreasonable to expect. It never happens. Anything under .25 is good to be considered a smooth ride. Most balancers actually automatically round up or down to the closest .25 oz. Unless the operator has chosen to see the actual numbers.

Even the .48 you specified seems a bit suspect.. If you were only out of balance by that much on one tire only out of all 4 I wouldn't expect you to be able to feel it.

My first question when reading was do you have aftermarket wheels or stock? If they are aftermarket, do you have hub centric rings? and are they in good condition?

And to answer your #3 Q... everyone should have the tires re-balanced periodically. Id say every 10,000 miles. As the tires wear down, the rubber that used to be balanced is no longer there.

RotoRocket

iTrader: (1)

Thanks for the repkly, gh.

You are correct about the .48, because I was temporarily dyslexic and it was actually 0.84 'off.' I don't know if this makes a difference in terms of what you stated or not.

The wheels are all OEM; they're the original 18" factory Mazda alloy wheels that came on the car new from the factory.

And that's a big yes on the balancing. I'm going to start balancing/rotating my tires every 10,000 miles without exception.

godesshunter

After rereading your post, this stood out to me.

Question: How worn out were your previous tires? I get this complaint a lot at the shop from customers who install new tires after running their previous tires down to almost nothing.

The bald tires give a false sense of stability much like racing slicks. This happens over time and too gradual to notice. Until new tires are put on with fresh tread.

When you go from very shallow tread to new thick tread the car will feel like it is wandering. Its the result of the weight of the car squashing and squirming the high treads around. I bet it feels like your high speed steering input is delayed...

It more common with snow tires in the fall. However the "feeling" happens also to people who drive sporty cars and are very in tune with how their cars feel on a day to day basis rather than normal old soccer moms.

I suggest giving it a couple weeks for your senses to adjust and see if the feeling has dissipated.

40w8

I had Hankook Ventus V12 225/40r18 put on the front with Enkei 18 x7.5 wheel and no balance.

They have no shake or shimmy up to 120mph, but I did tell them to install with the yellow tire marks near the valve stem like they should be for closest balance.

The rears were accidently balanced, but ride the same: perfect.

IMO that if you have out of balance after half worn, it's really the belts getting lose inside the tire, not out of balance.

RotoRocket

iTrader: (1)

Old tires were pretty worn down. They were slightly cupped, too, b/c I hadn't really been staying on top of the balancing & rotation, but they actually rode fine (but were pretty loud).