Wheel info (offset etc.)

Peaty · 01-15-2004, 05:02 PM

AFAIK the offsets are the same through the years per model, however I'm not positive. This here is from an 02' Impreza

Peaty · 01-15-2004, 05:03 PM

This is for an 02" Legacy/Outback

Peaty · 01-15-2004, 05:03 PM

This is from the 03' Forester:

Stock XT Wheel = 19.0 lbs
Stock XT Tire = 19.6 lbs
Steel Spare Wheel = 24.4 lbs

edit: adding 06 Forester info which includes the 17" wheel

Peaty · 01-30-2004, 07:00 AM

EHobron from NAISOC answered my question nicely regarding offset:

------------------------------

The simple answer is that the offset should never change despite wheel width. Even a 10" wide wheel will have a +48 offset on your vehicle. It would never fit the car but suspension geometry would be correct if you could bolt it on. I'll explain geometry in a minute. That's where it gets a little more complicated.

Offset is relative to backspacing and wheel width. That's why it's so confusing.

For example, with both wheels having +48mm offsets, the back spacing on a 6.5" wheel is about 5 5/8" while the back spacing on a 7" rim is about 5 7/8". Additionally, a 7.0" wheel with a +42mm offset would have backspacing of about 5 5/8". Note the similarities and remember this for the last paragraph.

Offset is the distance between the centerline of the wheel and the mounting surface of the wheel. Positive offset occurs when the mounting surface is outward of the centerline of the wheel.

Suspension geometry in basic terms is determined by drawing a straight line from the center of the upper ball joint, through the center of the lower ball joint and down to the center of the contact patch of the tire. Since that line is rarely perfectly plumb, the wheel is OFFSET to make the contact patch of the tire sit in the correct position. The offset is determined by some crazy smart engineer with way too much education.

Since offset is calculated using the centerline of the rim, offset will remain the same regardless of wheel width.

One of the reasons problems occur when choosing wheels that are too wide is that backspacing is changing. In the case of high positive offset wheels as are used on most sport compacts, the backspacing increase is noticed more at the inward portion of the wheel. This is evidenced by rubbing on inner fender skirts, the sub-frame, or even on suspension parts in high negative camber applications.

Take some measurments. As long a you have at least 1/4" clearance from the innermost edge of your wheel/tire, you can choose a 7.0" wheel with a +48 offset. The 1/2" added wheel width will be divided equally to the inner and outer edges of the wheel. 1/4" on each side when compared to the stock wheel.

On the other hand, changing to a +42 offset would move the wheel outward 1/4" so the entire 1/2" width change would be noticed only on the outermost edge of the wheel. The result would probably be no clearance issues inside but parts wear "might" be increased.

Bottomline, I recommend you stay with +48mm offset on the 7.0" wheel.

I hope this helps reduce some of the confusion.

Good luck,
Eric

Peaty · 06-02-2005, 02:00 PM

some new info:

Tribeca info

Wheel Offset is 55mm
Bolt Pattern is 114.3 x5

From 2006 Tribeca Technical Service Manual

Peaty · 06-13-2005, 05:23 PM

04 WRX and WRX STi wheels (note the 05 STi has a different bolt pattern 5x114.3)

Peaty · 11-27-2009, 10:32 AM

Good info here too:

Click Me

Peaty · 07-26-2010, 05:55 PM

some wheel info. Dated but could be helpful

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Installing 04 STi Steering Wheel on 04 WRX (w/ cruise control)	wrxakaboosti	Interior	1	07-08-2008 03:30 PM
'04 wrx stock alloy wheel offset?	04 WRXWAGON	Q&A Archive	2	03-22-2007 01:27 PM
HowTo: 4 wheel alignment (toe and thrust angle)	nhluhr	FAQ	3	01-09-2007 12:28 AM
WRX Steering wheel on Impreza	kastle	Interior	2	08-01-2005 10:00 PM
Wheel Offset	BPCLFD	Q&A Archive	16	10-08-2004 11:15 PM

Sponsored Links
ScoobyMods Advertisement