Given that your main goal here is to fit the most rubber under those fenders, I think installing rear spacers may be a necessary evil as they will change the offset. One downside of using less negative offset is increased load on the bearings. The rule of thumb, I remember reading somewhere, is changing the offset more that 2” will stress out the bearings and they will wear out prematurely. I think that for a track only car it may not be an issue to use say 1” spacers, as negative offset is really more for balancing the load on the bearings while driving in a straight line (i.e. street use).

Also, although probably not important, a wider rear track width will have some minimal effect on the suspension stiffness. A wider track alters the car’s motion ratio and gives the wheel more leverage against the spring, hence effectively softening the wheel rate.

I think one always gains better cornering performance by increasing the car’s front track width. Why, because if you think about it, when the car turns in at corner entry, weight transfer goes primarily towards the front outside wheel. At full “g” cornering, the car is basically traveling around on three wheels. The “right triangle” formed between those three wheels is your “traction platform”.

So ideally what one would like to do is increase the “height” of that right triangle (formed between the front outside wheel and the “hypotenuse”, i.e., the front inside to rear outside wheels). Increasing the height of that triangle then effectively helps reduce the negative effect of too much weight transfer to the front outside wheel and give’s your “traction platform” more cornering potential. Remember, weight transfer is good, to a point, but beyond that, it becomes the situation of “robbing Peter to pay Paul”. A more balanced weight distribution on that traction platform will give better cornering performance, than say, one with the front outside wheel over loaded.

Increasing the car’s front track width is the best way to accomplish that.

However, using spacers or wheels with less negative offset, to increase the car’s front track width will have the unwanted effect of reducing the cars front “negative scrub radius” hence driving the car over bumps becomes literally a handful (LOL). Using the widest wheels possible up front while retaining near stock offset becomes a better approach. YMMV.

 

Nice post Mr Truch. We just don't see the word hyponenuse nearly enough in our daily lives.
Going up to the same wheel size on the fronts as these rears should help increasing the front track while maintaining stock-ish offset. (Now 60et) They're bigger than my 285/30 R888s and in radius too. That's the one thing with slicks, they tend to have a considerably larger Outside Diameter. See the 295/30 Pirelli R spec vs the 285/660 Falken slick.