What it takes to mount Jetta wheels on a Prius, if you really must.

Hi Folks, I have consulted this forum for a couple years since we got our 2010 Prius, and have appreciated the good advice. I thought I'd join to post some information I have found difficult to track down, and maybe save somebody some time and aggravation.

I was looking for a set of spare rims for snow tires. I found that actual Prius wheels were running about $100 a piece via local salvage yards, and they rarely showed up on Craigslist. That was too much for me, so I looked at the Prius wheel specs - 15 x 6J ET 45 (i.e., 45mm offset), 5 x 100, 54.1 mm center bore. This is the kind of stuff one needs to know, but 90% of Craigslist ads for wheels don't list it. Most will list what the wheels had been on, so I used website wheel-size to check for the missing specs. (Not always right, it lists different numbers for the 2010 Prius than are on the wheels themselves and in the owner's manual.) I eventually found a set of snows on 2002 Jetta steel rims at a good price, and very close to Prius specs - 15 x *6.5*J, ET *42*, 57.1 mm center bore. I obtained 3 mm hubcentric rings from eBay to address the difference in center bore.

Well, now comes the hard part. Lug nuts. Another "simple" thing that turns out to be complicated. The Jetta uses lug bolts rather than nuts, so I needed to find nuts that would (a) fit the Prius studs (M12 x 1.5) and (b) seat properly in the Jetta wheel lug holes. The Jetta seat is not conical, it is what is known as a radius or ball seat. Now the second part of the hard part. I was able to find ball seat open M12 x 1.5 lug nuts, but I noticed they did not seem to fit right on the wheel. Upon further research, I found I had gotten ball seat lugs with a 14 mm radius. The Jetta wheel takes a 13 mm radius lug (and finding this info on the internet is just about impossible). But it's not a simple matter of ordering the right lugs -- I can find lug nuts with a radius of 12 or 14, but not 13 -- only lug bolts with radius 13. After all, only certain German autos use the 13 radius, and those that do use bolts, so who could possibly want lug nuts in that size?

Ok, so that's pretty much a no-go if you want to be confident that your lug nuts won't loosen. I have just discovered that there are washers made to solve this problem. For example brandsport sells a "Lug Nut Washer Tapered/Ball Adapter" that allows 60-degree conical lugs to be used on ball seat wheels. I assume that the washers conform to the precise radius needed when you tighten the lugs. So there you have it, if you want to mount (these) Jetta wheels on the Prius, you need 3mm hubcentric rings, 20 M12 x 1.5 cone lug nuts, and 20 adapter washers. And probably some wheel covers.

Now, is it worth it? I have just learned that certain Michelin and Continental all season radials have snow & ice ratings almost as good as dedicated snow tires. Not having to change wheels, or store the set not in use and its accoutrements, and not having to mess with the TPMS? We're going to try these tires! Keep it simple!