New HO Tires

[RichD]

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.

[TuscoTodd]

Rich -
I would definitely be interested in hearing details on the source when your testing is complete. I have been running slip on tires from both RT-HO and Balls Out Racing in diameters slightly smaller than that and getting reasonable performance - but not quite what I see with the silicone coated sponge.
So count me as "intrigued"!
Look forward to hearing your updates!
:D

[RichD]

The tire size that I mentioned was chosen based on a great deal of careful testing that I had done about seven years ago. I did post a summary of those results on several of the slot BBs at that time with the disclaimer that they applied to my track, my car and my driving and that other testers might have somewhat different results.
I was deliberately vague about who was making the tires and what they were actually made of. Right now all anyone that is interested in testing these tires needs to know is what size they are and that they are slip on tires. Testers would receive some conventional silicone slip-on tires, some of the new tires that are the same size and also some 0.170" diameter double flange wheels. Potential testers would need to have a track with a timing system.
Another set of test tires is on the way, once I have finished running on those I expect to publish some lap times.

[Norman]

Looking forward to new tire choices, Dr. D !
I'm finding out the silicone on sponge tires don't like the heat in my garage.
Will these be rounded on both sides?

[RichD]

The new tires look about the same as Super Tires Pro Series tires, they are only rounded on the outside.
All of the tires that I have been testing will expand as the temperature increases. Right now it is 79°F down in my basement and they now measure 0.341". The Wizzard tires are marked 0.336". All of my earlier testing was done during the colder months and I was able to do that at 68°F. I have no way of cooling the basement, all of the tires may have more grip at higher temperatures.
I have found that some silicone on sponge tires are more durable than others, I have had no tire failures during a race. I keep an eye on the condition of the tires and replace them if I see any edge damage or wear. If you fail to do that the silicone is likely to peel off at an inconvenient time.

[RichD]

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 is 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.

[RichD]

I have tested batch 4 and 5 tires with the batch 5 ones being a tenth faster than regular slip-on silicone tires. A second tester has gotten the same results, so things are looking good. A third tester also has the tires, we are awaiting his results. Batch 6 tires that are a bit harder than batch 5 are on the way.

[RichD]

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 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 also be tested. 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.

[noddaz]

This sounds very promising. Please keep reporting on these tires.

Scott

[Norman]

Hey Dr. D - how do you think the new tires compare to Pro Series Super Tires?

[Norman]

Oops, just read your Aug.1 post! :violence-smack:

[RichD]

With the latest tires the difference was 2.56 laps in a 12 minute race, that would be just over 130 feet. Besides doing lower lap times the car felt more secure with the new tires. When you compare regular slip-on silicone tires to silicone on sponge tires that is also part of the difference. There are several advantages to slip-on tires besides the lower cost. If you race on many different tracks the tire that works best on your home track may not work as well elsewhere, if you have to pull off the wheels and press different ones on before a race that is a pain in the neck. With slip-ons tire changes are quick and easy. In the past however you would almost always be better off with silicone on sponge tires if you are looking to win races. We are trying to develop a slip-on tire that can go head to head with the best silicone on sponge tires so the racer will have the best of both worlds.

[RichD]

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.

[RichD]

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.

[RichD]

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.