Radical RXC Blowouts

I keep having Blowouts on RR tire at Daytona. It blows out on the inner sidewall and has the appearance on an underinflated sidewall but it's at target pressure(28psi). I'm running -2.5 deg of camber and 3mm in of toe.

I believe that the toe may be too aggressive for such a fast track(i.e. it overheats the inside wall due to toe and camber combination), so I will try running 2mm of toe in.

I was wondering if anyone had any other suggestions as to what might be causing the Blowouts, or solutions to try if this doesn't work.

Not something most us will have experience of, but it would help if you said how the tyre was failing - at the bead, the inner shoulder, somewhere in the middle of the sidewall? Is the wheel width within spec' for the tire used?

The right rear gets very heavily loaded on banking, especially with the amount of downforce you're going to be able to run - you may recall some years back when F1 was to be run at an Indianapolis most cars had to pull out because the tyres their supplier had made weren't capable of running the banking without overheating and failing? Is this the only banked you're running and, if not, does it happen elsewhere?

What are the tyre temp's across the tread, tread wear, is there evidence of blistering, how did you establish the 'target pressure' - is it the hot/cold pressure recommended by the tire supplier, that seems a little high on the toe-in - is it the factory setting, is it possible it's picking up heat from braking, etc? Any other info' that may be of help?

The tire is failing on the inner shoulder. It ends upseparating the sidewall from the rest of the tire. We were running sticker tires during both blowouts, the tire size and hot pressures are manufacture spec. The toe and camber settings are manufacture spec as well. At the time of the blowouts we did not have tire temp monitoring equipment so we are not sure of the heat gradient on the tire. There is no abnormal wear on the tires when they blowout, only the new two piece design lol.

Daytona is the only track we have issues with. As far as banked tracks, the only other one we run is Watkin's Glen and we had no issues.

Side note, the car with the blowouts issue is a Radical RXC GT3, we are also running a Radical RXC Spyder which is running the same tires and alignment and have had no issues. The GT3 is a closed cockpit and is about 350lb heavier, 370lb if you include driver weight.

My best guess - remember, it isn't something I have experience with, just read of - is that the while the maximum banking at the Glen is about the same as at Indy, the speed, and hence loading, is higher at the latter, and for longer. Entry and exit speeds may also be higher?

Have you talked to your tire supplier's tech'support, your competitors running similar vehicles and/or Radical about the problem? I suspect you're going to need to run more pressure because of the loading on that particular track to reduce carcass flexing and breaking down from heat build up.

Well you came to the same conclusion that we did. I've been talking it over with my boss and our plan is to run 2mm toe, add an extra 2psi to the RR and add a little crossweight to compensate for the overinflated RR.

As far as the tire failure, we sent one of the tires to Hankook for failure analysis over 9 months ago and still haven't heard back(most likely due to the pandemic).

I do cornerweights and Alignments till I'm blue in the face at work but sometimes I need a fresh perspective on problems. So thanks for your quick responses. I'll keep you updated on how it goes, we're running This Sat. and hopefully Sun.

I'm rather surprisedf Hankook didn't get back to you - is it a spec' tyre for the series you run in? If so, I would have expected then to have a tech' guy/gal at the tracks to give support.

You may wish to look at other series that are normally run on road courses and see it they, or their tyre provider, has recommendations for the banking.

Must be a damn scary thing to happen - I assume you have multiple changes of underwear for the driver at hand?

Update, the Radical RXC GT3 ran fine for the 1st 3 sessions, however the RXC Spyder blew a right front crossing start/finish. We then decided to remove camber from the RF tire on the Spyder and leave camber where it was on the GT3. We sent the drivers out for a few laps and told them to follow closely and run the same line. The Spyder consistently had lower tire temps, so we decided to remove camber from the right side on both cars and we set them up at the end of the day.

The next day, with both cars on a new setup we monitored tire temps and achieved very consistent readings between both cars and all tires. And no more blowouts!!

Now we're going to set down the cars so we now have a proper setup for the Daytona road course.

It's not a spec series we're running with these cars. It's just customers trying to have some fun, but we take every opportunity to collect data and fine tune the cars, because we're going to be running the Blue Marble Radical cup here in the states.