Quote:
Originally Posted by Flash68
Rob, so are you gonna redo your wheels and run something like a 285 on a 13 inch wide wheel? 
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DG I sent you that picture in confidence.
Quote:
Originally Posted by Ron Sutton
I figured before we move on to discuss Roll Centers, we should wrap up our conversation on steering geometry.
If your car has a large-ish scrub radius … you have to be careful with how much caster you can put in the car … because caster combined with a high scrub radius creates a “jacking effect” when you turn the wheels. Dynamically, this jacking effect “de-wedges” the car … loading the inside front & outside rear tires more … while also unloading the inside rear tire & increasing the degree the car diagonally rocks & loads the outside front tire.
All of this helps the car to turn better. But go too far … and the car will get loose on entry. This is where track tuning comes into play. If you have a large-ish scrub radius … sneek up on the caster you put in the car … until you get the car “free” on entry … then reduce the caster a tick … or tune something else to allow you to keep that amount of caster, so the car turns well in the middle. But don’t keep a set-up that makes the rear step out on corner entry.
Make sense?
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Ron
What would you consider Large-ish scrub radius in the case of these 275-315 range of tires?
I have heard that an inch or under can be thought of as zero.
Maybe a little more detail on scrub would be good.
I was having a conversation stating there is a nominal effect on scrub due to height differences in tires. That difference in scrub between a 30 and 35 series tire of the same section width on the same wheel would be pretty minimal and in real world probably insignificant. But with all things it is best not to assume and really dig into what amount of scrub becomes noticeable or detrimental.
