Truing rubber tires

[WB2]

How about a quick primer in truing rubber tires?

I’m used to urethanes. Up to this point, the only thing I’ve done with rubber tires is slap them on the rim and run.
Specifics: Tire Razor; SlotIt P6s glued to plastic SCX rally wheels on SlotIt axles.
I used 320 grit with water and a light touch to try a quick truing but can’t get a flat contact patch. I only see trace amounts of material that was removed.
Suggestions!

[HomeRacingWorld]

Well, just guessing of course...but what voltage? I know they are glued...but just curious if expansion is an issue?

And it might shock a few folks just how unevenly molded a rubber tire can be. As in the video I showed doing the Carrera fronts, it takes quite a but to get a 100% clean sand.

I think you just need more time...low and slow is the best approach and I'm sure you are doing that.

[Kevan]

4v

[chrisguyw]

Well,........truing rubber tires is certainly different than truing urethanes.!!...urethanes are a relatively quick process,...they cut smoothly and evenly, ...they are quite heat resistant,....whereas rubber needs to be cut slowly (3/4 volts), ...you need to make very light cuts, and,.. you must be careful to not overheat the tires, or they will "melt" and not cut cleanly.
You can true a pr. of urethanes in a couple of minutes,.....rubber will take significantly longer.....patience

So.........

1/ Glue the tire to the wheel(s)
2/ Use no more than 4 volts (I often use 3)
3/ Make very light cuts........turn the knob on your razor until the tire just touches, wait just a few seconds, and then back off the razor screw so the tire is no longer in contact.
This process is repeated until the tire is true,....again, after truing urethanes, rubber takes forever.

Once the tire is true, treating the tire with oil/lighter fluid will dramatically improve its performance/grip, but, that is for another thread

Cheers
Chris Walker

[WB2]

Thanks for the help.
Not sure of voltage since I use a train controller and usually never have a voltmeter connected. I was aware of the heat issue so wasn’t running very fast.
I found a YouTube video where the guy uses oil as he sands (on the car, not on a tire truer) rubber tires. Anyone?

[Kevan]

One thing I overlooked was your choice of 320 grit, that's going to take forever, try 80 grit.

[WB2]

A switch to 80 grit worked wonders.

[chrisguyw]

Thanks for the help.
Not sure of voltage since I use a train controller and usually never have a voltmeter connected. I was aware of the heat issue so wasn’t running very fast.
I found a YouTube video where the guy uses oil as he sands (on the car, not on a tire truer) rubber tires. Anyone?

Wait until after the tires are trued, before treating...............oil will soften the tire (which is good from a performance perspective), but applied during the truing process, it can make the tire too soft to cut cleanly.........and truing rubber tires (with oil) while on the car, is a bad recipe , as the "softer" tire will tend to grab the sanding material, and bounce/chunk/tear/gouge........you will just not be able to hold the tire in a uniform/consistent position against the sanding material.

Cheers
Chris Walker

[dw5555]

You can true a pr. of urethanes in a couple of minutes,.....rubber will take significantly longer.....patience

This isn't the 1st time someone has said this and I don't know how you do it that fast. I run the razor at 6v with 220 grit on PG tires cutting in .2A increments and it takes me at least an hour a pair, sometimes longer.
Dave

[32lbking]

Same experience here Dave. Since we are doing 1/24 tires I can see it taking a little longer. I have only done about a dozen pair and am still figuring it out, but none have been less than an hour.

[Vision34]

We run strictly nsr super grip rubber and stock thunder slot rubber. Glue and true. We run 100 grit and if you want end with 320 you can. Round off the edges. We do it at 5v. Then we soak them with nsr rubber treatment. By putting some on a rag and running the truer as it spins rubb it on till it gets hot. Our club experimented hundred of compounds. And they settled with treated nsr super grip. Clean it with lint tape and run what she brung. After running the car and before putting it away rub some nsr treatment on it and I will keep it treated till next running.

[Vision34]

In our scalextric stock class we run them with stock rubber. And same thing. Glue and true with nsr treatment and they get sticky. Scalextric trans am and modern and classic btcc all on stock rubber.

[WB2]

Intrigued with the stock Scalextric rubber.
I rather like the sidewall printing of the stock tires. At first I thought the DP stock tires would work, but ended up with P6 on one and PG on another.
I’m starting to think cleanliness is of utmost importance. SlotIt C1 and Ninco rubber was like running on ice. Until I cleaned the tires. When they went off, I cleaned them again. Repeat. Now they seem to work pretty good. Taken off the shelf, I do a quick sand with 320 W&D, then squirt some lighter fluid on a paper towel, run the tires on that, then off. For home use only.

[Rleog]

“Once the tire is true, treating the tire with oil/lighter fluid will dramatically improve its performance/grip, but, that is for another thread “

Chris, could you comment about using a solvent such as lighter fluid on rubber tires after they’ve been trued? I’ve seen how smooth the tire surface becomes after such treatment but I’m uncertain of how lasting or durable is the effect. Can this treatment be easily overdone and soften the surface, leading to more rapid tire wear?

[Kevan]

It depends what rubber you're talking about, nsr extremes will ball up real fast if you oil them. Nsr ultras like some oiling but too often and they will start balling up towards the end of the race. Nsr supers love regular oiling and don't seem to ball up at all but the high grip doesn't last as long as ultras. Don't forget there's no substitute for inherent grip that softer rubber has.
Of course as with everything else you have to compromise.