Your thoughts, advice: 16" OEM v-spoke wheel cracks/bursts!

[Cape Cod MINI]

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Had my dedicated snow tires removed today from the MINI 16" "v-spokes".
It was done at the local Firestone shop who has the appropriate mounting equipment. I did enquire before hand to ensure they had the right equipment and experience.
While adding air to one of the 16" Dunlop runflats the bead seated itself on the rim of the wheel and air was filling the tire. The wheel then burst in the middle! It's obvious that the air inside found a weak point and just blew a gash in the wheel/rim.
It's not on the lip, it's dead center in the wheel and about 3" long running clockwise as opposed to across.
Dealer says he'll look at it and "see what he can do" regarding warranty.
Firestone shop says there's no way they are responsible because it's an "obvious defect". I wonder though, if it's an "obvious defect" why did it blow when they were working on it and not any other time? I figure they were blasting air in and when it finally seated they pumped it up to 80-90 pounds and ruptured it.
Fortunately I have my 17" s-lites w/ Pirelli's and put them on so I'm not that inconvenienced.
Any thoughts on the rupture cause, warranty, how to determine if it was the shop's error or a defective wheel?

Post note: *I checked out the machine they mount the runflats on. Max air pressure on it is 60 psi and it was set at 45 psi so it doesn't appear they could crank it up to 90 psi and blow the alloy wheel out.

[Bilbo Baggins]

Sorry to hear that!

IMHO, the wheel needs to be looked at by an engineer familiar with material failure ASAP. Contact MINI/BMW right away. This sort of failure is something that they would want to see, can we all say LIABILITY.

Keep us posted on what happens. Some of us, like me, are running the same wheel as our main wheel. I just put my "V-spokes" back on after the winter. I was running the 15" "7-hole" wheels as my winter wheel.

Voids in the casting of the wheel are not uncommon, and this is what I expect was the cause of the failure. Forged wheels reduce the occurance of voids because of the pressure used in the manufacturing process.

Good luck.

[HarryHBMCC]

I run V-spokes as my winter wheels but I don't swap tires on and off them. I leave my winters on them and just change wheels for summer (playing the waiting game right now on when to put the summers back on). But I'll check my V-spokes out when they take them off (had them balanced recently and they were OK).

Harry