The spring keeps the lug nut...
The spring keeps the lug nut centered and attached to the wheel so wedon't need to use a pliable glue. The spring attachment point allows thelug nut to turn inside the spring wire while zipping it on during aquick pit stop.
Another use of split back spacing would be to line up the driveshaftfrom a top view. A lot of attention is now being paid to reducinguniversal joint angles, from any view, and the rear end can be relocatedlaterally by the use of different offset wheels. This may necessitateusing odd offset wheels at each end of the car on each side, but ifperformance is enhanced, then it is worth the trouble it takes to keeptrack of the wheels.
High amounts of back spacing can result in increased brake rotor heatdue to the rotor being placed farther into the wheel shell and out ofthe flow of air that would normally help cool the brakes. This, in turn,serves to heat the wheel excessively and that heat is transferred to thegas inside the tire. As the gas heats up it expands, and the tire willgrow in pressure more than if the rotor was located farther outside thewheel.
Pressure Bleeders
Some tracks and sanctioning bodies allow the use of tire pressurebleeders. These units will hold a certain pressure, but pop off andbleed gas as the pressure rises above a pre-set level.
This allows the team to start out the race with pressures closer to theoptimum race pressure and still maintain that ideal level once the gasinside the tire expands due to the heat. If a team is not allowed to usebleeders, they must anticipate the rise in pressure and start out with amuch lower pressure so that as the heat and gas pressure grows, it willnot exceed the optimum pressure needed for producing a proper contactpatch footprint.
Do not let your wheel get...
Do not let your wheel get to the point of being bent and battered.Sooner or later, the rim may break and the small cost savings youexperience from reusing worn wheels will translate into a high cost ofreplacing a front end or worse. There is a high degree of lateral loadthat the wheel must resist. Most wheels are less costly than a tire, andwe replace tires on a weekly basis most times.
Some teams use two-valve stems when using a bleeder system so they canfill or deflate the tire with a standard stem while not disturbing thebleeder valve.
Lug Nuts
There are several types of lug nuts that can be used. The standard typeof racing lug nut is fine for everyday use on most short tracks. If pitstops are a must, a spring mounted lug nut is available that staysattached to the wheel and also has a flanged back side which makes italmost impossible to hang and get stuck in the lug socket.
There are specially designed racing lug nut sockets that have widerradii to help prevent the lug nut from getting stuck in the socket, acommon occurrence during fast pit stops. These are a necessity for anyteam, whether pit stops are normally required or not. We never know whenan unexpected problem will require a quick stop to replace a flat tire.
Final Thought
Maintain your wheels and inspect them often. Don't let a fatigued orbattered wheel cost you a race or possibly a front clip. It would be agood idea to rotate the wheels from side to side occasionally due to thefact that the stress is only being felt on opposite sides of the wheelfor left- and right-side wheel mounts. Replace your wheels after hardcontact with the wall whether they are bent or not. Small cracks mayhave developed that the eye cannot detect. After all, it's yourinvestment and especially your driver's health we are most concernedabout.