For the last 2 years, I have run 19" Tenzo rims on my tC with 225/35/zr19's but just a few days ago I went back to the stock rims (powder coated satin black). Call me an old man, but I was tired of the road noise and the rougher ride of the 19's. Before swapping the wheels/tires back stock, I did some sound level readings in several spots that I regularly drive and at controlled speeds. Of the three areas I tested, I averaged an in-cabin sound level of 84 dB spl. I was running General Exclaim UHP's at the time. Then I swapped to the stockers with 215/45/r17 Continental ContiProContact's and I measured the same three stretches with the same conditions. I read an average of 74 dB spl in-cabin over the three areas. That's a 10 dB difference JUST FROM TIRES/WHEELS! I knew it would be quieter, but I had no idea it would be this significant. No doubt, the stock rims aren't as nice looking as the Tenzos, but I'm enjoying a more comfortable ride for now.I know that there are other variables such as the size/quality/brand of tire that are contributing to the drastic difference, but I'm just sharing my specific experience and results. I'm selling the Tenzos for now...maybe I'll buy some different rims in a year or so. Who knows?

 

Its a pretty obvious and logical formula:

low profile tire + larger diameter wheels = more road noise, less comfort, better performance

larger profile tire + smaller diameter wheels = less road noise, comfort, less performance

In my opinion I would say this applies about 90% of the time depending on the type of car. But in our case (the tC), which isn't exactly the most luxurious car, the formulas apply. You shouldn't need a dB reader to figure this one out, but hey, its always nice to have some numbers. Just thinking about it though, 84 dB, that's only 10dB less then most aftermarket exhausts these days. That's crazy.

 

Exactly why I run 16's and a 50 series tire. I drive 50+ miles on the highway a day and the more noise your car makes, the faster you fatigue.