Originally Posted by Jack Smash
I was running 1 degree camber on my 1/12ths on the new carpet track here. After a day of running, I had a slight coning of the front tires to the inside. I tried .5deg the next time out. The tires were wearing evenly but the car was now horrible to drive. Made the car hook hard on medium speed corners and had a really bad on power push. A few other guys had the same thing happen to them too. I don't think even tire wear is a definite indicator of how the car is working. If the car is fast and drives well, i wouldn't worry about uneven tire wear unless it is really severe.
Using tire wear to examine setup is a highly used process in scale racing and is applicable to RC. However, there are a lot of variables to consider and understand in order to use it effectively.
A few thoughts:
* Your goal should be to get even tire wear on the side of the car that takes the outside of most turns on the track. For most clockwise tracks it should be the left side. And vice-versa for counter-clockwise tracks (normally where Oval is run as well). The less used side will almost always have more coning on the inside edges.
* I always target a slight coning on the inside of the rear tires, to ensure that I don't chunk them. Something like, for every .3mm of wear on the outside edges I should have .4mm to .5mm of wear on the inside edges, depending on the amount of rear toe-in. More rear toe-in will create more coning on the rears inside edges.
* A track layout with a large sweeping corner at the end of the straight will almost always make the outside front tire wear more than the rest. Just rotate the front/rear tires from left to right after each run and true the rears down to match the fronts after no more than two to three runs to keep the diameters close.
* The front tires are the tricky part as camber gain and front end chassis roll play a big part in how they wear. In Jack's case above, reducing the camber, made the front tires contact patch increase when the power wasn't being applied fully (less chassis roll). However, when he went full on-power, the cars setup must be allowing a good bit more chassis roll, which effectively made the car ride on top of the outer edge of the tires. This reduced the front tires contact patch on-power.
In order to try to show the *trickiness* of using tire wear to adjust setup, here are a few options (not all) I would have considered in Jack's case:
- Less complicated: Adding more front camber gain by putting more angle in the front upper links (lower the inside or raise the outside) would raise the front roll center slightly and also increase the camber as the front end rolls. This might kill both birds with one stone if its enough of a change.
- More complicated (tried only if I already had maximum allowed angle in the front upper links) Adding front caster should cure the on-power push as it effectively increases the front camber as the wheel is turned to full lock. However, it may also cause the car to hook even more in the medium speed corners (neutral power). So I would probably have to either increase the front spring rate (alternatively stand up the front shocks more), raise the front roll center for less front end roll, or lower the rear roll center to plant the rear end more. I'd try the springs/shock angles first. If they don't work, then I'd raise the front roll center. I probably wouldn't try the rear roll center change as it will add more push on-power as well.
As Jack put it, if your car handles great and your satisfied with the lap times, then leave it alone and true the tires down after a few runs.