Hoosier A6 vs R25 compound tires

[jdp526]

Hoosier has the A6 compound in 13" dia with four widths, 225 to 255. I wonder how much better this compound would work compared to the R25 if available sizes would work on my FC?

Has anyone else tried this tire on their formula car?

[ahowe]

The compounds are very similar. The biggest differences will be the construction - bias ply vs. radials and cantilever vs. not. And this construction difference will potentially make a huge change to the car's setup.

If you are limited in rim width, you will find the A6 construction to be a severe hindrance. I have mounted a 225/50/14 on a 6 inch wide wheel (Miata), but it was far from ideal. A stack of four mounted is inches narrower than an unmounted set. All that pinching rounds the tread, "crowning" the tire.

Also, my experience with the A6's is that they require a relatively high tire pressure. The sidewalls are not anywhere near as robust as our R25's and the tread is much thicker. I doubt they would be happy at the low pressures we run on the bias ply slicks. And a higher pressure will make the contact interface far from ideal.

Andy Howe
Autocrosser - currently FF and formerly Miata/S2000/Boxster

[DHale_510]

They seem to want about 3x the camber too, at least it works that way on sedans and Miatae. My FC Crossle 63 does not have anywhere near that much adjustment.
Dennis

[jdp526]

Thanks, Andy, I think I will stick to the R25 tires after reading your assessment.