Explaining why lowering tire pressure helps steering

[AllJumpStyle]

Interesting point, I had not considered this. I'm not sure this works in all cases though. Consider the extremes:

• comparing a 33" tall tire to a 10' tall tire with the same mechanical trail. For some reason, I can't visualize that the 10' tire would respond the same as a reasonable sized tire. One difference I can see would be that the pneumatic trail would be much greater on the larger tire, due to a longer contact patch.
• Another extreme scenario would be a tire so short, that the caster approaches ridiculous numbers (think +45°).

It's the trail that changes though, not the caster.

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[AnnDee4444]

It's the trail that changes though, not the caster.

Yeah, I'm not sure why I didn't realize that this morning (probably due to the time change).

The larger diameter tire has more pneumatic trail, meaning it can have less mechanical trail (caster) for the same total trail.

 

[Jeep&dogs]

It's the trail that changes though, not the caster.

Yes the actual caster doesn’t change but the effect of the caster changes because of the increased trail. On my Lj with a 33 I was able to run 4* of caster and it handled great, when I put a stock 30’ tire on it when I was doing the paint work it drove like crap. Totally different vehicle with the taller tire. On my JLUR the stock 33 Didn’t handle great in my opinion, going to a 35 there was a noticeable difference. Going with the longer Mopar arm was a even bigger difference.

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