EBMCS03

Not sure yet... in the works... but managing all the funds right now to see... see now its another extra $100 some for alignmnet... is it worth it is it worth it...

CENTRAL CALI

Good luck can't wait to see what you get

EuroCarFan

I went to 20s and did not do an alignment. Car feels dead center. I might have the dealer take a look though, since I have active steering. Would probably give me a peace of mind. You'll definitely need an alignment if you lower your car but not necessarily true if you're just upsizing your wheels/tires.

Heloha

Sorry if this is hi-jacking the thread but here 2 follow-up questions to EBMCS03 great topic:
1) If you change wheel and tire sizes did you have to re-calibrate your speedometer?
2) What are the optimum suspension settings? (Like camber, caster, toe-out)

EBMCS03

1.) Heres my take, Not if you keep the diameter of the wheel the same... so meaning your sidewall on the 19 will have to be less than on the 18s...

2.) I dont know... someone else can attack that.

znod

No alignment for me going to 19" PS2s. But, I am going in tomorrow to have my right front re-balanced. I am getting slight bumps at 75+. My dealer told me to hold off until I had several hundred miles since the PS2s sometimes apparently need some break-in time before all is well.
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Folks with the E46 M3 have had nothing but troubles with the PS2. Vibrations galore - I believe there was even a de facto recall of some of those tires as they were produced out of spec.

Every new set of tires, I follow this proceedure....

1. Receive tires from TireRack.
2. Have tires mounted and balanced at local TireRack installer
3. Drive imediately (usually with a shimmy) to high performance tire shop for:

High Speed (135+mph) on Car Balance
Tire Trueing(Shaving) on car as well

Drive home is smooth as glass.... I've have also read, trueing tires will actually extend tread life by reducing friction with road surface.

From my experience, the slight shimmy/vibration will not correct it's self as it causes uneven tread wear....

Take it for what it is worth ... probably not much.
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Thanks much ipse d. I'll post back how the next step works out. I may have to find a high-performance tire shop. I have never heard of one in Phoenix, but hopefully I'll find one if I need it.
[/quote]
All is smooth as glass again. Had a major bolt in my left rear. BMW rebalanced all wheels/tires to make sure and fixed the hole--all free.

ipse dixit

What do you mean by "optimum suspension settings"?

The settings will all depend on what you want the car to do and what you plan on doing with the car. E.g., are you going to track it? Drive it the grocery store and back? Cruising down long stretches of straightaways?

Depending on what you want to do, your camber, caster and toe settings will all differ

Camber
If both the right and left wheels are positive cambered (that means they leans to opposite direction), the steering tendency will be cancelled so that the car remains running in straight line. If the car is turning into a corner, weight transfer put more load on the outside wheels than the inside wheels, that means the outside wheel's steering tendency will have more influence to the car. As the positive-cambered outside wheel tries to steer the car to the outside of the corner, the car will be understeered.

On the contrary, if both wheels are negative cambered, the car will oversteer.

Toe
For minimum tire wear and power loss, the wheels on a given axle of a car should point directly ahead when the car is running in a straight line. Or, in other words, the toe angle should be 0 degrees. Excessive toe-in or toe-out causes the tires to scrub, since they are always turned relative to the direction of travel.

With the steering wheel centered, toe-in causes the wheels to tend to roll along paths that intersect each other. Under this condition, the wheels are at odds with each other, and no turn results. In this way, toe-in enhances straight-line stability (usu. means good for those long trips where you are just cruising along).

If the car is set up with toe-out, however, the front wheels are aligned so that slight disturbances cause the wheel pair to assume rolling directions that do describe a turn. Any minute steering angle beyond the perfectly centered position will cause the inner wheel to steer in a tighter turn radius than the outer wheel. Thus, the car will always be trying to enter a turn, rather than maintaining a straight line of travel (usu. good for auto-x).

The toe setting on a particular car becomes a tradeoff between the straight-line stability afforded by toe-in and the quick steering response promoted by toe-out.

Bottom line: toe-out encourages the initiation of a turn, while toe-in discourages it.

Caster
If the caster is equal but too negative, the steering will be light and the vehicle will wander and be difficult to keep in a straight line. If the caster is equal but too positive, the steering will be heavy and the steering wheel may kick when you hit a bump. Caster has little affect on tire wear.

Positive caster tends to straighten the wheel when the vehicle is traveling forward, and thus is used to enhance straight-line stability.


Hope this helps and sorry for the long-winded post ...

poleposition

YES, you need an alignment. Don't let anyone tell you differently. Before I put my 20's on, I did extensive research on this specific issue and you most definitely need that alignment. You're not driving a Trans Am. You have a technologically advanced automobile. If you don't get it aligned, you'll probably notice nothing but you'll be thinking about it constantly. The smallest variation will offset your tire wear. Spend the money, factor in the cost. Peace of mind is well worth it.

Heloha

I guess my "optimum settings" question stems from my autocross days when I raced my 87 Corvette. Just doing dome slight tweeking on the that suspension gained a lot of corning abilitly with little noticeable tire wear. On the Vette, I went for the maximum amount of Caster, about 1.0-1.5 negative Camber (bottom of wheel out), and about .25 degree toe-out.

I was hoping someone may know if there are settings that may optimize the handling without too much additional tire wear. I know it is give and take / trial and error, but just wanted to know if anyone had changed from factory settings.

arosamond

Maybe a real stupid question but if you change the tyre size will this have an affect on the speedo reading?