Alloys paint blistering

UK user...

The car is just approaching 3 years of age. Two of the 427 style alloys are starting to blister very close to the TPMS valves. Not large blisters, but it has started.
When it went in for its end of warranty check yesterday, I highlighted these blisters and the dealer said it was not covered because 'the blisters are not in the centre of the wheel!' I'm not happy with this, for blistering to happen so soon, it doesn't bode well for the future. Anyone else suffering the same?

Any info on the paint code for these alloys would be appreciated as I feel this should not go unchecked being so close to the valves. The dealership says they will call BMW but I'm not hopeful of them actually doing that or BMW offering to get it sorted under warranty.

My wife i3 has these wheels which have winter tyres and are on the car from around October to April. Purchased new last year and no sign of any corrosion yet. That said, she also has summer tyres on 428 diamond cut turbine alloys. White worm or corrosion under the lacquer had started from the centre out. Car was still within 3 years warranty and I asked BMW to inspect. Quick look (not sure if they measured paint) and they said it's not covered and wheel had been refurbished. We've absolutely no idea if they have been repainted, but I'm doubtful.

The wheel was subsequently put to a wheel company and diamond cut and repainted with lacquer. Think it was around £150. Corrosion is there again around a year and a half afterwards. On diamond cut alloys it's pointless trying to run them in UK climate, unless they are only on for summer months. Not sure where you are, but an alloy in all weathers is vulnerable as water, salt and brake dust will pool at the valve.

In your case on 428 alloys, you're probably looking at around £80-100 to have them refurbished per corner, refitting TPMS sensors.

Not sure on colour code, but on VAG alloys, paint is made by Wurth.

Update. I stuck to my guns and complained. After a further inspection it was deemed that the blistering paint was caused by the fitting of the TPMS valves. Having date checked the tyres etc, they agreed to provide new rims because no replacement valves had been fitted and the tyres on two of the rims were fitted from date of first registration. The cause must have been down to the production line.