Do Trued Tires Stay True?

[HO RacePro]

I've recently acquired a Professor Motor tire truing machine and have been spending plenty of time going over the tires on my cars. I true the tires until I see no (and I mean not any!) runout as measured with a standard dial indicator.

Now I am wondering if a glued and trued set of tires will go out-of-true as they wear. Should I be touching up my tires before race events? Is this common practice or is it not necessary?

The most likely cause I can see for tires wearing out-of-true would be variations in the rubber's properties around the circumference of the tire. Those might be caused by the molding process -- how the rubber is poured or injection molded. But it might take a significant amount of wear before a tire becomes measurably out-of-true.

I doubt tires would go out-of-true just in storage -- properly stored so there is no weight on them. I could be wrong. It happens.

No, I think practice laps would be the cause. How many? That would be the question. A few dozen? A few hundred? A few thousand? TBD.

Ed Bianchi

[docdoom]

I have not seen any go out of round but I have had to re true to get the tire contact even again because of uneven tire wear.

[Aptosc6]

The glue bond between rim and tire breaks down over time. As this happens centrifugal force will spin out the tire effecting the roundness of the tire. Always a good idea to check your glue bonds after each race and re-glue and tire as necessary.

[Kevan]

Well there's just two reasons tyres go out-of-true

[HomeRacingWorld]

You will want to "touch them up" over time. Tires will wear as they run to the track. Many of our oval cars can get "coned" shaped over many miles. The force going into the curves and flex of the tire, regardless of gluing, will effect the contact patch.

[HO RacePro]

Many years ago I raced in a sprint car series on a commercial banked oval track. I deliberately 'coned' my tires, as well as angled my front axle, so my car would roll in a circle rather than straight. The idea was to improve cornering speed while I fully realized I was sacrificing some straight line speed due to 'crabbing'. I hoped my car would get around the corners fast enough, carrying more exit speed onto the straight, and with a bit extra braking, to make up for the slower straight-line speed. Result: Great cornering, not enough straight-line speed. Mid-field competitive. I probably overdid the tire coning and axle steering. Never experimented enough to find the sweet spot.