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Re: What relationship? Posted by sam96CS [Email] (#852) [Profile/Gallery] (more from sam96CS) on Sun, 7 Jul 2013 11:56:16 In Reply to: Re: What relationship?, AdamB [Profile/Gallery] , Sun, 7 Jul 2013 03:45:04 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The 25 mm offset agrees with the offset Saab chose for the 15" x 7" Super CS wheels that Fondmetal made for Saab about 20 years ago. I know because I just measured one.
Now let's compare what happens when a 6-1/2 inch wheel with a 27 mm offset is replaced with a 7 inch wheel with a 25 mm offset:
1. The center of the tire's contact patch moves 2 mm towards the outside.
2. The inner wheel flange moves 4.4 mm towards the inside.
3. The outer wheel flange moves 8.3 mm towards the outside.
Note that 4.4 mm + 8.3 mm = 12.7 mm = 1/2 inch, so I have accounted for all of the added 1/2 inch of width that's gained by going from 6-1/2 inch to 7 inch rims. I got these dimensions by drawing 2D wheel elevations with CAD software. I can post a picture if anyone wants it.
The overall result is a slightly wider stance. I'm not aware of any suspension changes Saab made to Super CS models. If no changes were made, then Saab must have calculated that the stock suspension could handle the changes.
As TML noted, an offset smaller than 25 mm would move the wheel toward the outside. I don't know what tire Saab specified for the Super CS models, but it probably is a 195 or 205 mm wide tire. You have very slight contact on the inner side of 225 mm tires. We don't know what offset Saab would have used on 7 inch wheels if they intended to specify 225 mm wide tires.
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