I need to know stock rim size and what will fit 1986 vw scirocco?

For tyre sizes do you understand what all numbers mean? I've described them below just in case you don't.
If your changing tyre width you need to adjust the side wall size. Changing the rim size will also need the same adjustment. Generally a narrower tyre will need a taller side wall to keep the wheel size correct. The wrong tyre size will affect your speedo reading and affect the handling and grip of the vehicle.
To drop to a 16 inch rim the 225/55R17 would have to be either a 255/50R16 or a 215/60R16.
To go up in rim size the 195/70R16 would have to be a 255/45R17 or a 285/40R17.

Using the 225/55R17 - 6.5J x17 as an example.
Tyre size.
- 225 is the width of the tread on the tyre in mm.
- /55 is the side wall measurement as a percentage.
- R is the tyre is a 'Radial' construction type.
- 17 is the rim diameter in inches.
Rim details.
- 6.5 is the width of the rim between the points where the tyre attaches to the rim.
- J is the code for the shape of the seal edge.
- 17 is the rim diameter in inches.

GO TO A GOOD RIM AND TYRE SPECIALIST.
There are set measurements when rims are fitted. As long as these match you can fit any make of rim.
Take your car details they will be able to suggest rims that will fit.
If you don't, things get complicated.
You will need to check the following.
-Number of wheel bolts/nuts. (4 or 5).
-wheel bolt/nut spacing. (Distance between opposite holes).
-Rim diameter.
-Rim width.
-Rim offset. (How far the rim sticks out of the wheel arch.
-Rim edge type.
-Tyre size.

The number after the r is the rim size. According to your post you have 17 inch rims. Stock rims were 15 inches or optional 16 inches. Unless you are putting a different size rim on then you need a17 inch tie to fit your current rim

Here's what you need to do. You need to get the tire size off of the tire on your vehicle. Lets say its P205/75R14 or something like that. Go to this link, type that size into the tire on the left, then you can change the tire on the right to whatever size you. You will be amazed what will fit on that vehicle. I wouldnt go over 20" rims if i were you. 22's will leave you very little tire and a very bad ride.

Here's some info on your bolt pattern and wheel offset.

1990 Buick LeSabre 5 lug 4.53 inch or 115 mm High Positive Offset

Heres the tire size calculator
http://www.miata.net/garage/tirecalcold.html

Any question, comment back. If you are looking for 20" rims, 255/30/20 is a common tire that you can find reasonably cheap and lines up perfectly with most vehicles.

Mercedes is same bolt pattern but they use a 12mm stud/bolt so the holes need to be enlarged to 9/16" (14.28mm) for your 14mm stud/bolts.
This is not an exact fit but I have run them and it works dandy and the turbine wheels look great in addition to being about 1" wider so I can use lower profile passenger radials instead of the skinny reinforced ones.

if u have a grand am gt--gt1--[se1--se2 w touring package]stock tire size 225/50/r16 [16 inch rims] if urs is a se--se1--se2 stock tire size is 205/65/r15 [15 inch rims]

depending on what you are looking to do with your truck. 2 sizes larger then stock listed. Wheel changes? 205 >215 16" plus 2 > 215>225 etc
17" with same results , remember though,,the manifactor intended these sizes for a reason. Too much outside bearing pressure will set off the complete stability of the drive train

the stock rims should be 16" making the tire size 205/55/16. let me know if you have a different rim size. you can look at the tire size on the tire sidewall and the last number is going to be your rim size. if it's a 15' rim the tires are 195/65/15 and finally for 14" rims the tire size is 195/70/14. hope this helps.

I would advise you to leave both sides with 235 45 17 this tire size would provide you with better handling and improved comfort also tires wil be more protected of suffering damage in the sidewalls caused by bumps and potholes just remember to keep them inflated at 38 +/- 2 psi.

Other than VW, not many. May not be worth the troble of trying to see if any other foreign cars use the same size/design rims.