Brian Evans, Mid Ohio Pirelli tire tearing

I have been looking at the article published in Road Racing World’s 2008 Track Day Directory and I am going to purchase your DVD next week but I had some specific questions for your about tire wear.

I had a look on your website at the ‘tire-wear.html’ page and I noticed I have some of the very same issues which you are detailing. Included below are some links to images of my tire wear. I am using Pirelli Daiblo Superbike Slicks or Diablo Supercorsas, depending on what is available, typically in the SC2 compound at Mid-Ohio, a newly paved track. I know most of this info is overkill but I would rather be thorough.

Typically I will set my tire pressure cold, about 3 below at the rear and 3-4 below at the front AND I use tire warmers for about 45 minutes before I go on track. I noticed that you are stating 5-7lbs is a more ideal gain. Should I be setting my cold pressure this far below where I want to be? According to my notes I have the sag set at 43mm front and 28 rear.

Any help is appreciated, unfortunately I keep destroying tires and there is little knowledge on this issue around here… Here are the pictures of my tire wear…
http://www.redstarwebdesigns.com/bikes/images/026.JPG - front left side
http://www.redstarwebdesigns.com/bikes/images/028.JPG - rear right side

Brian Evans
Senior Web Analyst


REPLY:

Hi Brian,
Thanks for the email and the detailed information. The tire wear is disturbing as it is eating tires and killing your wallet.

Front tire looks like a geometry tear to me given what I can see. The bike may to too nose heavy with too much bias to the front wheel and that will result in what appears to be a rasp file shaving the tire away. The rear tire is a pressure and rebound problem by looking at the tearing and the triangulation of the tearing around the tread pattern.

With the AMA team I work with we have the SC2 rear and SC3 front tires on the warmers for 90 minutes to equalize the temp between the tire and the rim. Then we set the hot pressure at 31 front and 28 rear. This is the only way that we can stop these tires from tearing. We double check it by having the riders come in at full pace so we can get an accurate read on hot pressure.

Has your gauge been calibrated?

Assuming sag is set as per your email, I would recommend setting the tire pressures hot from here on out.

NEXT - I would change your geometry radically to lower the back or raise the front by 8mm to see what happens to the front tire. Dont' go in small increments!

NEXT - work on rear shock rebound. Go 6 clicks in both direction to see what that does to the tread pattern.

Let me know how things proceed and how I can help you further.
Many thanks,
Dave