The Kaytee 12' silent spinner is pretty good. I purchased it for my rats and I love it. It doesn't make any noise at all whatsoever and it either clips onto the cage or has a stand which is handy . They're on Amazon for pretty cheap or PetSmart has them also.
A 12 inch wheel is the absolute smallest you can go, for an adult rat. It's better if you can get a custom made one that's larger. You can get 16", "homemade" wheels on Ebay. They're listed for chinchillas, but rats love them too.
You might want to try a "saucer" type wheel. You'll still need one that's 12 inches, but they also come in 14 inches.
Don't worry about the "silly factor"... If your rat/s enjoy having a wheel, it's what they like, not what you like.
Not all rats like or use a wheel. The ones that do like a wheel don't care what they look like. Just make sure, if you get a wheel, it's large enough to accommodate an adult rat.
I have 3 of the SS wheels. They seem to work well for me... At least, when my rats use them lol. They are easy to wash as well, which is important because rats tend to LOVE to pee on them. :/
Good luck with your wheel!
I dont mind my silent spinner but its definitely not completely silent lol. It doesnt squeak but kinda rattles... then again mines 3 yrs old and chipped/cracked in places! Out of the 6 rats i have owned, one was a hard core wheel lover and 2 run sometimes. The others have ignored it.
I have the magnum wheel for my rats. It's basically the stealth wheel, but for rats. It cost me around 50 dollars, but the price was completely worth it. It's completely silent, and my Lynn can run her marathons on it while I'm sleeping at night. I've had it for a whole year now.