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In our group we run D124 non-mag cars on urethane tires. On race day we are allowed 2 cars to use for 6 12 minutes heats. It seems the tires last about 36-48 minutes before they start to fade. So to stay competitive you need to switch to your 2nd car for races 5 and 6. After each race day you have to retrue your tires if you want to have a chance at winning. This is A LOT of work.

So, my question is, how often do you retrue your tires?

Bruce

I rarely re-true. Most times they just need a cleaning. I run the tires on a sponge pad with alcohol to clean them off.

Me too. Once trued, I rarely have to do more than clean them off with a pad, or even tape. My track is pretty heavily banked, and I don't see uneven tire wear till almost 5,000 laps. Probably no help on your question, but that is my experience so far. I might add, I run some very heavy cars too.

Bob

Bruce I don't retrue at all. Once glued on and trued it's simple cleaning.
I have found on a test I did that a reasonably round urethane tire will actually break itself in with about 100 test laps, and that a trued tire will also change to the bevel that suits it. .This has more to do with chassis flex and set up than a tire fresh off the truer.
Bob

We're thinking between the weight of the cars and, most likely, excessive tire spin the tires lose there trueness, if you will. On wood, i could understand them staying true longer. On plastic, I could see them losing their true due to 2 things. 1) the excessive tires spin. 2) the same spinning over uneven track joints. I would think that would nip away over time???? On a normal race day we're turning 390-400 hard laps with a 1.50 pound car.

Bruce

On my glossy finished masonite track, I ran with silicones for 2 or 3 years.
When I switched to urethanes they would glaze over after 20 or 30 laps.
I'd have to clean them, only to get the same results. I had to scrub my track several times with alcohol & even lacquer thinner until
the urethanes would work well. I seldom clean the track now. As a matter of fact I think the urethanes work better with more "marbles". :D
Now I only occasionally clean them like Harry says.

If I haven't run the car for a while I will spin the rear wheels on some very fine wet and dry sandpaper - 1200 -2000 I find that helps.
When racing I clean the tyres in between heats - we use shellite.
We also use lint cleaners to clean the tyres some people use masking tape as well

Bruce - are you seeing beveling, graining, chunking or just glazing?
(I am assuming you aren't loosing roundness - but contact patch?)

i would say grainy or dull.

Bruce I'm sure I'm preaching to the choir here, but just in case.
On wood tracks I use A shorehardness of about 37 to 43.SH
On plastic it works much better with about a 50 SH.
Some of the urethane are made down to 25 or 30s which give great grip on wood but I wouldn't use on a lengthy race. For me on wood it's softer as mentioned and in plastic it's harder. Another thing to consider to increase grip is to true the tires but then run them backwards just before the race on 800 grit . It seems to open up the urethane a bit for better grip on plastic, for wood once true, polish with 2000 grit wet dry.
If you get a new tire with that nice shiny surface and the tires are close to true, it's amazing the grip you have, which goes away once the Shi y surface breaks in.
As for the contact patch, it will adapt itself to the track you are on. When you see the tire start to bevel so the outside is smaller than the Inside it is as a result of the car tipping slightly on the corners and creating a contact patch on the corners but smaller on the flat and level. Not necessarily a bad thing. I usually put about a 3 degree bevel on my tires when truing.
Bob

I'd like a nice grippy set that wears out in 200 laps!

Thanks for all the tips. I've never heard of running them backwards.

Bruce

You won't be able to run them backwards in a digital Carrera though :(

lol, i think he means backwards on the truer, not the car on the track.

Bruce

I have no experience with running urethane tires on a 1/24th car and my experience with silicone tires on 1/24th cars is limited to commercial tracks in the '60s. It is harder to diagnose tire problems on a plastic track than on a wood track. If your tires are even a little out of true they will make a drumming noise on a wood track, on a plastic track that noise would be masked by the noise that a car makes when it passes over the joints. From reading what you have posted elsewhere I gather that you only run on urethane tires, that would rule out the problem that you would have if the tires were getting coated with the residue that silicone tires might leave on the track so simply cleaning the tires is not the solution to the problem. You did not say if your tires were glued or if you were running on an oval or a road course. You also did not say if your cars wanted to slide around much when they are on fresh tires. On an oval track the tires would start to cone and would need truing for that reason, it is much less likely that you would have that problem on a road course. You also did not say how you were truing your tires. If you are using a machine you can easily get the tires perfectly true, otherwise you will never get them perfect and that may be the reason that they tend to go off rather quickly.
Part of your problem is that you are running 1/24th scale cars, which are not terribly popular, so the selection of tires that you might try is limited. Silicone tires are a lot more durable than urethane tires and they also have more grip providing that the track is perfectly clean. It might be a good idea to get some Quick Slicks silicone tires that fit Carrera wheels and give those a spin in "as is" condition. Even without being trued those might have as much grip as trued urethane tires. Silicone tires are much more difficult to true than urethane tires, if you needed to true them you would probably have to use a machine of some sort.