I'm wondering if anyone runs 255/35/20's up front and if there's any pictures with what it looks like. I did a search and saw that someone had, but I'm not sure if that was a misprint. I'm mostly worried about rubbing since aggressive canyon driving already causes some wheel well scraping.

I like going to the track occasionally with the meaty slug CLS (road course, not drag) and the couple times I went, I swapped out my front 20's (245/30/20) because there just wasn't that much meat to protect the wheels in case I got aggressive on turns and wanted to go over some curbing. I already dent enough wheels just on LA streets.

Since I sold the stock wheels, I can't really do that...and it was somewhat bothersome to swap out anyway. Since I'm lazy, I'd rather just run meatier tires on my car for the random times that I'll take this car to the track.

or a 245/35 for that matter

I don't drive CLS55 but I do drive CLS550. I am running 245-35-20 in the front and no issues at all. My car is lowered with links but its NOT slammed. I asked the same question few weeks ago on CLS550 forum but everyone said no and will not work how ever, I know guy who is running 255-35-20 in the front and I PM him. He said he has not issues at all. I am going to try 255-35-20 in the front next time.

Here are some pics.

If your stock height, it should work. If you plan on lowering your car I would stick with 255/30/20. My car still rubs the fender here and there with the 255/30, but then again my car has an aggressive drop.