what would be the biggest tire to use? 225/40/18 shouldnt have any problem in the font? and about a 275 40 in the rear

the under carrige of my 86 looks preaty good except for one corner that is rotted out bad. my question is what can I do to prevent it from falling appart and keep it in piece? I thought about spraying that under-car rubber coating in a can stuff. should I give it a layer of spray paint first? should I sand or just pray over as is?

What's a good in dash DVD player for $350 or less? Is it possible to find one that plays DVD/CD with a flip up screen for this price?   It doesn't even have to have the flip up screen, some of the models with the little 2 or 3 inch display would work also. Wife has a factory am/fm radio in her jeep and it's killing me, no tape or cd in the thing.

rubber berring? on steering colum. I have the rubber boot all riped up and the berring or whatever it is does not seem to be in the best of shap. Can I replace this? Or does it not matter.