I had time to do some tyre testing on the drag strip, using one Micro Scalextric chassis and Audi TT body...
I used six types of Super Tires - four sizes that can be used in the Street Stock class and the 464s and AFX 490s that can only be used in Super Stock...
The Tyco sizes are all .280" (7.12mm) wide, the Mega-G tyres slightly narrower at .250" (6.36mm). The high, but narrow Aurora AFX .490" tyres are .200" (5.09mm) wide. All the tyres are silicone, apart from the Tyco .464 Pro Series which I only had the urethane version of.
All the tyres were measured on the same yellow Micro Scalextric hubs. I ran the car in for 5 minutes before the test and revved the car with the wheels off the track before every timed run. I also experimented with some weight (Blu Tack) in the nose of the Audi body, if the front of the car seemed to be lifting and the car stalling or stuttering - which was the case occasionally using the higher tyre sizes. The speed trap reading at the end of the strip is approximated using the length of car and the time the sensor is covered. Because of this approximation, the program rounded the speed to 6.793mph, 7.102mph, 7.440mph or 7.812mph in these tests.
Here's the data...
The speed for the AFX tyres should read 7.812mph - they were quick at the end, but not 80mph quick!
What I saw was a clear progression of lower ETs and higher speed trap readings, until we got to the two highest sizes. Although the 464 urethanes gave the quickest ET and average ET of the test, at least 0.5g of weight was necessary to prevent the front lifting, which caused poor starts and occasional deslots. The car was more consistent with the weight - and a wheelie bar would certainly have helped too. I don't know if the softer urethane compound helped or hindered that initial grip... The silicone version would have been good to compare. The Aurora .490" tyres caused problems at the start, although the car was rapid by the end of the strip. It's probably a combination of a little too tall for the motor/gearing - although that will be part of the fun building and tuning a Super Stock car.
In terms of the Street Stock tyres, the .448 tyres gave the quickest ET and average ET, although they did need a little weight - 0.2 to 0.5g - in the nose of the Audi body to help with the front end lift on acceleration. Because of the odd poor start with the bigger tyres, the smaller tyres gave more consistent times. The gap between the ETs was so small, that I think the .448s also make a decent entry-level Super Stock tyre.
This begs a question:
Super Tires want to send us all some tyres to play with - each competitor would get a pair each of two sizes. As people can buy the 448s (and lower sizes) from Barry at Slot Car Direct, should I ask for larger sizes that aren't available in the UK?
The .452R Pro Series tyre (available in urethane or silicone) will just sneak into the Street Stock class
The .464R Pro Series tyre (urethane or silicone) is the biggest in that series and came out well in the test for the Super Stock class. There are also two intermediate sizes (456R and 460R) in that series.
Any thoughts on which two sizes and which compound - standard silicone or softer urethane? Or the .452R in both compounds? I will also ask Nick and Sandy at Super Tires what they recommend.