Also, on page 9 in Downtime Files, there was a letter about 'Altitude and Tire Pressure'. Because I don't ride in mountains as much as I would like, I don't have the experience. If anyone is having a significant change in tire PSI due to altitude, I would like to hear about it?

Last year, I rode from chicagoland (elev. about 800 feet) to Divide, CO (elev. about 10,000feet) and didn't experience a significant change in PSI that made me make a note to be more careful. My best WAG is that I should have had PSI near 50+psi-rear/40+psi-front (up from stock 41R/36F) due to such a change in elevation. And I don't recall anything like that during my pre-ride checks.

Ok. This is a tire thread and I am wandering slightly away from 'cupping'. But, I see no harm in collecting related info here. And changes in psi should affect cupping in significant ways, right?

Dave goes into carcass stiffness. Anybody got any data on the likelyhood of stiffer carcasses being more/less prone to cupping? It would be nice to know that cupping is a pure tread pattern problem and has nothing to do with carcass construction. Or maybe it is a pure compound problem exacerbated by a certain kind of usage?

Ok, I have vowed to do a little investigation during sunday biker breakfast in the summertime when the bikers are plentiful. I'm going to look at a lot of tires and talk to a lot of bikers and maybe learn something about cupping.

Ever notice those tires at Deal's Gap aren't cupped? Granted, I was only looking at the ones showing the most shredding. Maybe cupping is a flatlander or gentle thing and and it doesn't occur where riders get to spend a lot of time going hard in the twisties?

Also, AFAIK,  I have never cupped a rear tire. It is a front tire only thing for me. And any cupping that I have had has been on a 'modern' high speed rated tire that looks like a slick with a few rain troughs cut in it having no 'sipes' whatsoever. 'Sipes' are the little side cuts off the main rain grooves in my little universe. The 'ribbed' front tire treads of old never cupped on my old bikes.

Anybody wanna take one for the team and ask Dave about this stuff? Right at the moment, I am not in the mood to contact Dave about all this. And I don't think that he will volunteer anything here, if he even reads this place or gets someone to report on me/us.

Aside: My Feb issue came with smudged ink in a cuppla places and real light print in another. I sent a note to Production Quality Control via the contact tab on this forum about the smudged ink but didn't mention the light print. So, if your issue is less than flawless and has light ink, you can mention it to the editors. this is the first time that I ever got a rag that wasn't perfect, production-wise.

nobody rides half as well as they know how.

That quote made me remember more than one track day instructor telling their charges to "drop your psi to 30, fore and aft from whatever your street psi is."  I am going to go way out on a limb here and say that I agree with and support Dave on that idea. Dropping a rear tire to 30psi from street stock 42psi just gives too much squirm, slip angle, and weirdness for most non-track riders to deal with. Dropping the front to 30psi from a street spec 36psi is also too much in my book. It would be better to drop it to 33psi and ride it a while to get used to the feeling. Then drop some more if one wants to try 30psi. My limited experience tells me that Dave's 4psi is just about perfect for me. 32psi on the front is pretty good. Soft enough for me to feel some slip angle creep. Yet hard enough that the tire goes where I want it and does not wash away without good feel that I am approaching its limits. I do not as yet ride so well that I like a mushy tire.

What has the above got to do with cupping? Well I had a fairly new front tire (2-3k miles on it) at the track for a day last summer. And I looked at the tire at the end of the day and saw no sign of cupping. If it was starting to cup from being abused for 120 miles of track, I couldn't see it? But, it is possible that I don't know how to see minor cupping if it was starting there? I shoulda asked one of the track rats but wasn't smat enough to know to do that at the time. Aside: From my POV, I would think that an expert on my bike would also need to be an expert on my fitted tire to recommend dropping psi more than 4psi to me?

Anybody wear out a set of tires at the track and get cupping there? Maybe it is a street only phenomena?

nobody rides half as well as they know how.

Take care, Mike

I spent most of my life on my motorcycle, the rest I just wasted.