# New HO Tires



## Rich Dumas (Sep 3, 2008)

Recently I have been testing some new slip-on silicone HO tires. The goal with these tires is to match or exceed the performance that you get with silicone coated sponge tires. Silicone coated sponge tires have been the best performing HO tires for a long time, but they are expensive, they can have a short life, you must pull off the wheels and press on new ones to change tire diameters and a number of makers have dropped out of the picture so that type of tire has become more difficult to find. I believe that a number of clubs have switched over to running slip-on silicone tires for those reasons.
So what if someone could make a slip on tire with the same characteristics as a silicone on sponge tire, but was not as time consuming to make and thus would probably be less expensive. Having a more durable tire that could be changed without also having to change the wheels would be an added bonus.
Thus far the results of testing on my MaxTrax have been encouraging. The tires are 0.340 inches in diameter when they are on a 0.170 inch diameter wheel, for me that has been about the optimum size to use on a T-Jet SS or Fray type car.


----------



## Rich Dumas (Sep 3, 2008)

I just completed some testing on the third batch of tires last night, it was 79°F. I am not 100% certain what effect the higher temperatures might have on lap times, I know for sure that the tire diameters increase as the temperatures go up. The target tire diameter for the testing was intended to be 0.338", but now all of the tires are 0.340", possibly a little more. That only means that I am outside of the sweet spot for the lowest lap times on my track, but I believe that the comparison between tires of the same diameter are valid. In the future I will probably also be testing slightly smaller and larger diameter tires.




























The test car is a Johnny Lightning Camaro in SS trim, the car would turn in better lap times if it had a Fray style body, I may do some testing with one of those in the future. It would cost about $63 to build another example of that car.
The best lap time with Wizzard white 0.336 tires was 5.487 seconds, for regular silicone slip-on Pro Series tires it was 5.652, for the Batch 1 tires it was 5.529, for Batch 2 it was 5.478 and for Batch 3 it was 5.570 seconds.
The differences in lap times would not seem significant to people that do not race their cars, but after a 12 minute race on my 50 foot MaxTrax compared to regular Pro Series tires the Batch 1 tires would get you another 2.8 laps and the Batch 2 tires would be good for another 4 laps. Most racers would sell their soul to the devil for another 4 laps.
It looks like the goal of matching the performance of silicone on sponge tires has been met, but further testing by myself and other people needs to be done to confirm that.
The maker has refined his procedure since he did the first two batches, he will be sending me three sets of tires all made by the latest procedure since he believes that using the earlier procedure would result in batch to batch variations in the production tires.


----------



## JWSpeed (Jun 2, 2009)

It also depends on track condition. If I cleaned my track for slip-on tires, a silicone sponge equipped car couldn't come close to my lap times. If I did the opposite than my slip-on equipped car was like driving on ice.


----------



## Rich Dumas (Sep 3, 2008)

You did not say what sort if slip-on tires you were talking about. There are silicone, urethane and EPDM slip-on tires. Different materials will respond differently when the track is not perfectly clean.
Most of the testing that I have done was on a track that was as clean as possible. Before I started a series of tests I would strip the track down with naphtha, then run a magnet car around with wide sponge tires with a very small amount of traction compound on them. Finally I would run a spare car with slip-on silicone tires for at least 100 laps before I began testing. I would run a couple of air purifiers during the cleaning and testing. Even a small amount of dust will obscure subtle differences in tire performance. Of course you will not always be racing on a perfectly clean track, I have raced on filthy tracks and found no joy in that. Dust sticks to silicone tires and once they get coated they lose much of their grip, washing the tires or rolling them on sticky tape will remove the dust and restore grip. If a track is only slightly dusty running the cars around and repeatedly cleaning the tires will eventually pick up the dust where the tires roll. After that only cars that go off into the boondocks will get dust on their tires.
I normally test for how long the tires will hold up by running for 30 laps, that is about how many laps a decent T-jet SS can do in a 3 minute heat. I only try to run at perhaps 90%, so I won't have any offs that might get the car into a more dusty area. After 30 laps I go for the fastest possible lap time and compare that to the already established lap time for clean tires. 
When I was comparing silicone to urethane tires I did some testing with some dust on the track, that is difficult to do because silicone tires will pick up dust and urethane tires can push it around so the track condition may change from lap to lap. The best that I could to for a comparison test was to run one tire on one middle lane and the other on the other middle lane.
In addition I found that there was a problem with urethane tires if silicone tires had previously been run on the track. Silicone tires will leave a deposit on the track that sticks to urethane tires and quickly spoils their grip. To prepare the track for urethane tires I had to strip it down with naphtha and then run many laps with urethane tires before I could begin testing.
In the case of the latest round of tests I am mostly comparing the new tires to regular slip-on silicone tires, I had only included silicone on sponge tires during the first round of testing. The reason for that is because many clubs no longer are racing on silicone on sponge tires as I mentioned in my earlier post.
Thus far the results of my testing have been encouraging. The procedure for making the new tires has been modified, so more testing needs to be done. The tires will not be commercialized until more people have tested them.


----------



## Rich Dumas (Sep 3, 2008)

*More Testing*

A second tester has evaluated the tires and gotten results virtually identical to mine, so things are looking good. A third tester has the tires and we are awaiting his results as well.


----------



## Rich Dumas (Sep 3, 2008)

*Still More Testing*

I receive a 6th batch of tires. The Batch 6 tires performed better than expected, I was able to run many very low lap times without any offs. Our second tester got the same results. We will also be testing a new batch of tires to be sure that they are as good as possible. Because of the high room temperatures in both test locations the tires have all been bigger in diameter than what I would consider to be optimal, however the comparison with regular slip-on silicone tires of the same diameter should be valid. Some tires that are 0.004" smaller in diameter will be tested as well. That would give us 0.334" at 68°F and 0.338" at higher temperatures. If these tires get commercialized it is anticipated that they will be available in a limited range of sizes, probably 0.330, 0.334, 0.338, 0.342 and 0.346" on 0.170" wheels. Smaller or larger sizes are possible if there is enough of a demand.


----------



## Rich Dumas (Sep 3, 2008)

*Testing Update*

The latest news is that a third tester has gotten the same results as me and tester #2. I believe that his track is more twisty than mine and he has seen a 0.2 second improvement in lap times over conventional slip-on tires. In addition he has made similar comments about the improvement in drivability. Between us we have over 150 years of experience racing HO cars.
We will need to see how the batch #7 tires work before the tires are commercialized. It has been decided to offer ten T-Jet sizes. The batch #6 tires have rounded inner sidewalls. The new tires will be about half the cost of silicone on sponge tires.


----------



## Rich Dumas (Sep 3, 2008)

It looks like we have zeroed in on the best formulation to use. Production tires should be ready to ship in about a week, I will post a formal announcement when we are sure about that. On 0.170" wheels at 68°F the mounted diameters will be 0.322", 0.326", 0.330", 0.334", 0.338", 0.342", 0.346", 0.350", 0.354" and 0.356". At 80°F the tires will be 0.004" larger in diameter, if you like to cut things close you might want to take that into account. If you decide to give the new tires a try be aware that the size that works best for you may not be the same as what you are using now. If you are racing it might be a good idea to order a small range of sizes, say plus or minus a couple of sizes.


----------



## Rich Dumas (Sep 3, 2008)

*Ready To Ship*










The new tires are now ready to ship. Pro Series sizes 312R through 348R are available. On 0.170" wheels at 68°F the mounted diameters will be 0.322", 0.326", 0.330", 0.334", 0.338", 0.342", 0.346", 0.350", 0.354" and 0.356". Use the -SE designation, they are $6 a pair.


----------

