alignment after new wheels? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

SoCal · 10-08-2005, 12:15 PM

When will I need my wheels aligned after replacing my 18" wheels for another set of 18s as soon as possible after delivery?

www.WheelEnhancement.com advised me that they will balance the new wheels but that alignment will not be necessary since the car will have been aligned before I accepted delivery.

The new wheels will be the same widths as the prior front and back, but different offsets. The rear wheels will use spacers, and all new wheels will be about 7mm wider.

I thought it would be a good idea to drive the car 50 miles or so and then get the alignment checked back at the dealer. Is that truly unnecessary, if I don't notice any mis-alignment?

10-08-2005, 01:06 PM

SoCal, what wheels did you get? I asume you got your new car!

What size spacers are you going with?

mjw930 · 10-08-2005, 01:26 PM

As strange as it seems wheel width and offset will not effect alignment. But, different wheel specs respond differently to various changes to alignment so if you are competing with the car you might want to experiment with different settings.

Example, 18" wheels and tires may be able to get acceptable cornering with less camber since the slip angle of the tire is less.

MNBoxster · 10-08-2005, 04:00 PM

Hi,

You may or may not need an alignment once the wheels arrive, but be aware of any unusual feel or behavior and if found get the Car aligned ASAP to prevent premature wear to the Tires.

I assume you bought a Wheel and Tire Package? If so, be sure that they are dynamically balanced. Wheels and Tires, believe it or not, are not truly round. They are only round to within a certain degree ±. Dynamic Balancing is done on a Computerized machine which first Road Tests the Wheel and Tire by spinning it to 50MPH and then pressing it against a Roller to find it's Runout (eccentricity). It is not the same as Spin Balancing a Tire. Ask if they are using a Hunter GSP 9700 (best) or 9600 (they should be) Balancing Machine. Also, ask them for the printout for each Wheel/Tire, the machine will do this printout.

The Tech will then mount the High side of the Tire to the Low wide of the Wheel, or vice-versa before determining the Mass High/Low side of the Combo and adding a weight to compensate. If this is not done, especially on a Performance Car, Suspension, and Tire, you can get some vibration at a given speed which is not due to, or eliminated by, alignment.

And, there is an acceptable degree of runout and Mail Order Tires are notorious for being out of spec (do Manufacturers sell-off these Tires and keep the ones in Spec for their own Authorized Distributors? Who can say) , but the incidence of out of spec and near out of spec Tires is higher with these MO outlets. I have bought many Tires through such outlets as Tire Rack, Discount Tire, and such, but I always tell them I will have the Tires Dynamically Balanced and reserve the right to return any which are not within spec. I had to do this once. Hope this helps...

Happy Motoring!...Jim'99

Brucelee · 10-09-2005, 05:33 AM

I would realign and rebalance the car if I replaced tires AND/OR wheels.

Given the cost of our tires, I think this is prudent.

SoCal · 10-09-2005, 09:07 AM

Quote:

Originally Posted by bmussatti

SoCal, what wheels did you get? I asume you got your new car!

What size spacers are you going with?

My projected build date is October 24, so still waiting.

I'm getting the 18" 996 Carrera 5-Spoke wheels that were optional on the 2003 Boxster S. click here

Those wheels come in 8" and 9" widths -- the same widths as the 987 18" Boxster S wheels, which I ordered.

Since the diameters and widths are the same, I'm planning to take the tires that come with the car and have them installed on the new wheels. (What do you think I should do with the factory Boxster S wheels? Wheel Enhancement offers to take them as a trade in for a $900 credit.)

According to Wheel Enhancement:

The wheels on the 2006 Boxster S have the following offsets:

8x18" 57mm
9x18" 43mm

The 2002 996 Carrera 5-spoke wheels have the following offsets:

8x18" 50mm
9x18" 52mm

Using the 8x18" 2002 wheel with a 7mm more aggressive offset on the front is not a problem, the wheel will be well within the fender on the car. The rear 9x18" 2002 wheel sits too far inboard without using a spacer, affecting the handling as well as having a negative affect on the appearance. Using a 17mm Porsche Factory wheel spacer (and silver anodized lug nuts) will bring the rear wheel out 8mm further than the stock wheel, compatible with the front wheel's position.

(Edit: If you got the 2002 996 Carrera wheels as an option on the 2003 Boxster S, you got 7.5" wide on the front and 9" wide on the rear. The 996 wheels for the Carrera were 8" front and 10" rear. But since the 18" Boxster S wheels for MY2006 have 8" front, and 9" rear, I'm going with that same combo.)

10-09-2005, 09:30 AM

Hey SoCal:

Sounds good!

Why don't/didn't you order your car with the Carrera Classic 19" wheels. This is option code #405. The cost is $1,940. The wheel is very similar to the ones you have selected from Wheel Enhc. I suspect that you did not want 19's"

If you sell your Boxster 18" wheels on your own, I would suspect that you can get more than the $900 that Wheel Enhc. is offering you. Post your sale here...looks like stuff sells pretty fast.

Good luck!

SoCal · 10-09-2005, 10:12 AM

Quote:

Originally Posted by bmussatti

Hey SoCal:

Sounds good!

Why don't/didn't you order your car with the Carrera Classic 19" wheels. This is option code #405. The cost is $1,940. The wheel is very similar to the ones you have selected from Wheel Enhc. I suspect that you did not want 19's"

If you sell your Boxster 18" wheels on your own, I would suspect that you can get more than the $900 that Wheel Enhc. is offering you. Post your sale here...looks like stuff sells pretty fast.

Good luck!

True that I didn't want 19" wheels. I think the 18s provide a better ride and better handling.

10-09-2005, 10:17 AM

Quote:

Originally Posted by SoCal

True that I didn't want 19" wheels. I think the 18s provide a better ride and better handling.

SoCal, I understand what you are saying here about the better handling...but how did you determine this???

Thanks.

MNBoxster · 10-09-2005, 10:16 AM

@SoCal,

Watch that the change in Offset (a component of SR) does not affect the Scrub Radius of the Front Suspension. Too much change to the SR can make the steering real twitchy after turns (return-to-center is affected) or when going over even the slightest bump. There is no alignment cure for improper Scrub Radius. The resulting instability is often improperly attributed to Tire imbalance or such, but isn't and cannot be cured. Otherwise, they look great! Good Luck!...

Happy Motoring!...Jim'99

SoCal · 10-09-2005, 11:01 AM

Quote:

Originally Posted by MNBoxster

@SoCal,

Watch that the change in Offset (a component of SR) does not affect the Scrub Radius of the Front Suspension. Too much change to the SR can make the steering real twitchy after turns (return-to-center is affected) or when going over even the slightest bump. There is no alignment cure for improper Scrub Radius. The resulting instability is often improperly attributed to Tire imbalance or such, but isn't and cannot be cured. Otherwise, they look great! Good Luck!...

Happy Motoring!...Jim'99

I understand the concept of what you're saying, but I have never even heard of "Scrub Radius" before.

Is there any way the SR can be affected by only 7mm more width (for each wheel) on the front? If so, what can be done to determine whether I'm at risk, or how to address it? (I'm getting PASM too, if that matters.)

Can the SR be affected by adding width to the rear also?