Why does my car catch ruts so bad?

You misunderstood me. Or prolly I worded it wrong. The front track of my car is off from stock. The ackerman is wrong. They worked fine on my truck that they were built for.

 

All cars that I am aware of have a wider front track than the back, Look at some car specs and check it out. The manufactures do this so the cars will track better in ruts. As the car moves over and hits a rut, the first contact is in the front. This will hold the front and let the rear continue to move so the car steers away. If the rear hits first, it will hold the rear and let the front continue to move. This will steer the car further into the rut.
This is probably oversimplified but that is what the pro's do.

 

One of my first cars I bought had bias-plys on front, radials on the back. Felt like it was wondering all over the road even when it wasn't... it was the weirdest feeling.

 

X2 as a possibility

 

I don't think anyone has mentioned wear, have they?
One worn or loose tie rod or ball joint (especially ball joint) will cause that, and your mismatched tires will just magnify it. Jack that sucker up and check for anything with free play in it.

 

My first thought is not enough toe-in.

 

This is very true. Makes riding a motorcycle with old-style tires a real eye-opener as well.

As others have said, 40 psi is too much...it could very well be ballooning your tires enough to make the contact patch irregular. I'd start here, then go to an OLD alignement shop that doesn't rely on a computer to put the numbers "within tolerance". I did this with my '60 recently and it made a HUGE difference in the way it tracked down the road.

 

One day I was at a show and started talking to a guy that had a t bucket and his front wheels were wider than the back ,You physically could see the front shackles floating from side to side .He was going to put a panhard bar in the front to stop the wandering problem .I dont think that would work ..........Ive also had radials in the back and bias upfront .That created oversteer.I personally dont think you have alignment issues ,Im sure you probably know a guy .Alignment is priority one .And try different air pressures works great on trailers ....That wander at certain speeds/////