Optimum track width

[another69]

I have C5 bearings on an Art Morrison subframe, but I think this question is general enough to cover many other front suspensions. Should your track width be the same as your hub to hub measurement? It seems like this would be best for the hub bearings, but I don't know about what it does to geometry. The AME documents show track width as being narrower than the hub to hub measurement, but with my existing 17X8 wheels (will change as budget allows) my track width is actually about 7/8" wider than the hub to hub measurement.

[astroracer]

Keeping track width inside the "inner" bearing dimension is a good thing. Having it the same or slightly wider is relative to what you are doing with the car. The lever load on the bearings is what you want to keep lower and having the "fulcrum point" inside the bearings lowers that load. Altering the offset of the wheel so the offset is equal to or more then the width of the wheel will keep the fulcrum point, or track width, even with the inner bearing.
As an example:
I am using 17 x 10 front wheels on my van build. When I designed the suspension I designed the track width around a 7" offset on those wheels. This, of course, pushes the spokes out to the outer lip. A lot of guys don't like that look but for bearing life and suspension design this is what I needed.
Same thing in the rear. I have 18 x 12's back there with the same 7" offset as the front. This puts the fulcrum point 1" inside the wheel mounting face and about even with the outer axle bearing. Reducing load and hopefully increasing bearing life.
mark

[another69]

So would "0" offset really be best for bearing load? That would make sense. Are you saying that a positive offset is better for the bearing than a negative offset? In order for my wheels to clear my new calipers, I need to run spacers which make the offset even more negative, but I have no choice right now. I prefer the track to be as wide as possible as long as it doesn't hurt the suspension geometry or put an excessive load on the bearings.

[astroracer]

So would "0" offset really be best for bearing load? That would make sense. Are you saying that a positive offset is better for the bearing than a negative offset? In order for my wheels to clear my new calipers, I need to run spacers which make the offset even more negative, but I have no choice right now. I prefer the track to be as wide as possible as long as it doesn't hurt the suspension geometry or put an excessive load on the bearings.

The actual offset depends on the wheel size, suspension design and how much room you have in the fender. With my van I actually pushed the tire out past the stock outer fender to optimize the scrub radius on a fairly wide front suspension design. If I was using a narrower front rim, like a 7" wide rim, I could go with that "0" offset. Because I wanted (needed?) wider I had to push the wheel inboard to get the width. This going negative yes. Where the inner part of the rim is wider then the outer, pulling the "tire/wheel" inboard, or a negative movement. Those 15 x 10 with a 4" Back Space American 200s's I had on my '73 Firebird were a very positive offset, pushing the tire/wheel outboard toward the outer fender. Those deep looking rims are not very conducive to good handling as they put a lot of load into the bearings.
Mark