2005 XC90 alloy wheels rusted to rotor

I tried to rotate the tires on our 2006 XC90 V8 (alloy wheels) and just about wore myself out and bent 3 screwdrivers trying to hammer the wheels
off the hub. What a nightmare.
Turns out they were corroded onto the hub between the alloy wheel hole in the center, and the cast iron lip on the rotor. It's normally a very tight fit anyway, and the salt water (and regular water) got between the two. Evidently created a galvanic corrosion that caused such a tight fit it was nearly impossible to remove the wheels. It took a lot of hammering with a big screwdriver between the alloy wheel and the rotor (using the spaces between the alloy wheel spokes to get access to the mating surfaces between the alloy wheel and the cast iron rotor).
When I FINALLY got the wheels off (they VERY slowly loosened up), I scraped off the corrosion on both the cast iron rotor lip and the inside surface of the hole in the center of the alloy wheel. Then I applied a coating of Permatex Anti-Seize grease so that the wheels will be easier to remove next time.
To me this is an outright Volvo design flaw. Essentially the assembly of the two parts became a battery - two dissimilar metals (aluminum alloy rim and cast iron rotor) and an electrolyte (water/salt water). All are a recipe for tolerance-busting corrosion.
Anyone else encounter this problem? Does Volvo have a fix?
Thanks,
Mike
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I can say it is a fairly common problem for late model cars. The same question comes up fairly regularly in the Honda forum, where the hub-centric wheels practically weld onto the car. Your approach is the right one; antiseize on the mating areas and on the area where the lug nuts clamp the wheel down.
The recommended method for loosening the wheels in extreme cases (yours sure qualified!) is to loosen the lug nuts and drive gently a few yards, turning one way and the other, until the bond breaks. It can be too strong even for hammers and pry bars.
Mike
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Michael Pardee wrote:

What prevents this from happening on older cars? I've never had a problem with it myself, I suspect a coating of any sort of grease on the mating surfaces would prevent it from happening though. I don't see much difference in the hub and rim design between modern cars and 20+ year old cars.
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I don't know. My daughter's '93 Accord doesn't have the corrosion problem, but we don't use road salt here, either. People in the Honda forum report having to clear away corrosion on the interface in slightly older cars, but I can't say I've seen it affecting the really old ones. You'd think it would be more troublesome as years went by too, no?
Mike
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My 01 V70XC did the same thing. I use a hydraulic floor jack for tire rotations and simply loosen the lug nuts about one full turn from tight. With the wheel jacked up, I drop it kinda quickly and it will pop loose. A light coating of grease on all dissimilar and touching metals has caused me to do this only once.
Shawn
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Mike wrote:

This happens to all sorts of cars. When I bring home new ones, I remove the wheels and apply anti-seize the first day. Beats being stuck by the side of the road (in the cold, dark, and rain, usually ;-) unable to get the wheel off.
I think this is not a design flaw, but intentional. Much of the force applied to the wheel gets fed directly to the hub this way rather than the lug studs/bolts.
There is an easier way to break them loose, by the way. Loosen the lug bolts/nuts and back the car up. Stop suddenly. Repeat until the wheel is loose. Don't overdo it--you don't want to bend the lug bolts/studs.
JRE
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Volvo is far from the first car maker to have corrosion between two dissilimar metals. It's a fact of nature. The fix is regular rotation every 5,000 miles or so of the wheels and application of a grease of some kind.
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Thanks to all who responded.
I really like the idea several folks replied with - undo each lug slightly (1 turn max) and roll a few yards back and forth, braking suddenly to jar the hub loose if needed.
I did get them off and I did apply a coat of Permatex Anti Seize grease. The silvery stuff.
I have another newer car with alloy rims - I'll be doing the same grease job with them when I swap over to summer tires from winter rims.
Thanks again,
Mike

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