Originally posted by frozenpod
I used rubber tyres
But when I have used foam tyres I haven't had much of a problem with tyres wearing out unevenly. In fact they were almost perfect you couldn't tell a difference by sight only with verniers.
Overdrive does not work well with rubber tires on a nitro car. Many people assume overdrive is an aid to induce even tire wear over a run. This is far from true and these factors actually needs to be taken into consideration when using the overdrive system.
As the rears wear down faster than the fronts the car automatically induces overdrive from the bigger front tires at the expense of on power steering. Cutting (truing) the front tires down smaller than the rears improves on power steering especially with a one-way or solid axle in the front. With the smaller tires on the front you gain underdrive which makes the car push. To compensate you have to use the correct overdrive ratio to balance the roll out between the front and rear wheels again.
It becomes tricky to adjust because overdrive is not a static figure. As tires wear this figure changes (normally increasing in ratio). Over a longer 30-45min Main final this can cause problems and so many make the decision on whether they would rather be faster at the start and hope to build a good enough advantage or start with the car pushing the front knowing that the car will come to its best in the final stages were they can then launch a good attack on the other guys whos car set up has started to deteriorate.
Knowing the track and the wear rate of the tires over the given run time really help when setting the correct overdrive/underdrive ratio as you can roughly estimate at what point the car will be running at its optimum performance level during a race.