stupid question about big wheels

[Dreamcar]

When I look at beautiful chargers like Mr. Angry with 17s up front and lowered suspension, I often notice the top of the tire disappearing behind the fender. Can someone explain to me how the tires don't rub when the front wheels are turned?

[myk]

Keep in mind that a large rim doesn't necessarily mean a larger overall wheel/tire diameter.  For example I'm running 18" wheels, but the overall height/diameter of my wheel and tire can be about the same size as someone running 15" wheels. 

As for the rub you've got me.  The top of my wheel easily lines up with the bottom of my fender yet I almost never encounter any fender contact...

[Dreamcar]

Your right about the diameter...The cars I'm referring too are often lowered too, so when the tires disappears behind the front fender, I'm wondering how it doesn't rub when turned.

For example, Mr. Angry (one of my favs and inspiration for my build):

http://www.dodgecharger.com/forum/index.php?action=dlattach;topic=16220.0;attach=24557;image

[HPP]

The front suspension works in three dimensions and its the dynamics of camber and caster angles while moving through their arcs of motion. If everything is set up correctly, the tire does not contact the fender. Of course, that is assuming you have the backspace/offset equation of the wheels correct as well.

[Patronus]

Some cars have an air-ride suspension system allowing big overlaps. In this case you cant steer.

[HPP]

Yes, some have air ride so they can deliberately lower the car when parked.

However, alignment is a big part of how tires clear for those cars that do not use air ride. For example, if you set your alignment up with a -1* camber, the top of the tire will tilt in providing clearance to the fender lip. When that tire is compressed on a bump, by design it gains additional negative camber so at 2" of bump, that -1* may now be -3* and provide additional clearance.

Similarly, positive caster will pull the top of the tire slightly backwards in relationship to the wheel well. Because of the anti-dive and ackerman angles of the upper control arm, compressing it 2" will tend to not only pull it back, but in also. This motion is further accelerated if steering input is being put into play like going around a corner. Next time you are looking at your engine, look closely at the actual angle where the upper control arm eccentrics sit compared to the frame angle.

So a basic alignment spec of -1* camber combined with +5* caster can results in a -5* camber and a +10* caster when compressed 3" of travel and a steering angle of 30*.  That has moved the tire a considerable amount into a position where it is clearing a lot of sheet metal.  However, this is utilizing a non-stock specified alignment to start with.  Use the stock specs,a reverse offset rim that is popular with a number of aftermarket wheel buyers, combined with a 70 series tires, and you can have clearance problems with a 215 wide tire while another guy can make a 275 clear everything.

[Dreamcar]

Great info. Thanks!

[1974dodgecharger]

His suspension also lets him do that setup and look...