track width?

how does increasing track width affect handling?

How about changing the ratio of front to rear track

I'm interested to hear an answer for this as I have always wonder this myself?

Generally speaking, with all else being equal, the wider the track width the more stable the handling. Back in the late 1950s GM increased the track width on their B body cars, by 5 inches, and handling was noticeably better. Pontiac was the first to do it in 1958, the rest followed suit shortly after. The difference between the Pontiac B Body compared to the rest forced the others to rethink the engineering of their suspensions.

Increasing the track width will have the effect of reducing the wheel rate (spring rate accounting for suspension motion ratio) which can improve grip at that end of the car. As such it can be used as a tool to help balance the car in terms of an understeer/oversteer bias. There aren't a lot of absolutes here so it's a case of testing to see how your particular car responds with a track width change.

so to increase track width a person has what choices.....

Cheap way.......wheel spaces or Negative offset. Which will hurt scrub radius!!

Expensive way......all new longer suspension arms to push the spindle/steering knuckle outboard but maintain scrub radius?

Just curious to hear the common method leaning toward track use and not aesthetic

New engineered spindles are also another option.

The more track width will also tend to lower the total weight transfer while in a turn. Playing with diferent track withs front and rear you can change the total weight transfer in a turn per axle, and so tune the car for over or understeer. As lees weight transfer ocurs, more grip available in the tyres. This is due to tyre sensivity ( friction coefficient changing in relation to the load the tyre is suporting, at a decreasing rate. As more load is put on the tyre the less the friction coeficient is). This is why all real race cars tend to use the maximum track width that the competition rules allow. All of this i've explained ads up with what andre has explained too.