Car has felt "loose" since rim/tire change up.

[BluePonyGT]

I'm wondering how "balanced" your rims are. Did they have to add/remove wheel weights to balance the rims + tires?

Also does it get worse or better after the tires heat up? If it stays the same no matter the tire temp I'd be worried about the rim balance.

Finally, when I stepped up from stock rims to my Project6GR 19x10/11's (Michelin Pilot Spirt 4s tires) FROM the sad 18x8 rims with those horrible pirelli's the car hooked like crazy and drove totally different, but I could feel all of the looseness in the rear sub-frame. That led me down the path of ALL of the frame stiffening and getting rid of the hop + IRS supports. That helped a LOT.

So it could be a combo of things, but without knowing what else is in your setup it smells like an issue with rim balance.

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[magnetic17]

I noticed the same thing with 255/40-19 BFG G-force comp2 a/s roads where I live suck really bad and I have had alignment done to try and correct it but to no avail, really tired of this darting around feeling on uneven roads! glad mine aren't any wider!!

 

[Norm Peterson]

I noticed the same thing with 255/40-19 BFG G-force comp2 a/s roads where I live suck really bad and I have had alignment done to try and correct it but to no avail, really tired of this darting around feeling on uneven roads! glad mine aren't any wider!!

OEMs normally have this figured out pretty well for their OE tire and wheel sizes. So I'm thinking front alignment - as in a little toe out, which certainly can get 'twitchy'.


Norm

 

[1958cyclist]

For what it's worth, I changed to ForgeStar Wheels with custom Vorshlag offsets, 19 x 11 all four corners with Bridgestone RE-71R 305-30-19 and have had no issues other than higher corning speeds. :-)

 

[RaceHorseV8]

If excessive weights are needed to balance a wheel/tire a good shop will rotate the tire on the wheel and recheck for less weights to get it balanced. The fewer weights, the better and matching the tire to the wheel is more work but the best way to go.

 

[RalphK]

Are car tires like plane tires where you put the red dot on the tire (lightest side of tire) aligned with the valve stem?? Reason being last two cars had the red dot on sidewall all over the place and mucho weights.

 

[Norm Peterson]

There are two separate methods where you would align a mark on the tire with something about the wheel. Uniformity matching would not necessarily line up the same as weight matching. Nor is it guaranteed to result in only a small amount of balance weight being needed, only somewhere around the minimum required for that wheel and tire combination.

Uniformity Method (red mark)

When performing uniformity match-mounting, the red mark on the tire, indicating the point of maximum radial force variation, should be aligned with the wheel assembly's point of minimum radial run-out, which is generally indicated by a colored dot or a notch somewhere on the wheel assembly (consult manufacturer for details). Radial force variation is the fluctuation in the force that appears in the rotating axis of a tire when a specific load is applied and the tire rotated at a specific speed. It is necessary to minimize radial force variation to ensure trouble-free installation and operation. Not all wheel assemblies indicate the point of minimum radial run-out, rendering uniformity match-mounting sometimes impossible. If the point of minimum radial run-out is not indicated on a wheel assembly, the weight method of match-mounting should be used instead.


Weight Method (yellow mark)

When performing weight match-mounting, the yellow mark on the tire, indicating the point of lightest weight, should be aligned with the valve stem on the wheel assembly, which represents the heaviest weight point of the wheel assembly. After match-mounting by either of the above methods, the tire/wheel assembly can be balanced.

Norm

 

[RalphK]

Thanks, learn something new every day.

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