I bought an 06 srt8 gc and I was looking for some 20 inch black rims with a polished lip and It seems to be impossible to find a company that makes rims in 20's that fit that bolt pattern

the reason I need 20's is because I cant have any tires smaller than I already do due to the road/weather in russia

Contact DPEngineering. They have outstanding quality and make custom wheels.
http://www.dpengineering.cc/

would you happen to know how long it would take until I actually get the wheel once I order

It all depends. Mine took about 7 weeks, but I know some people have had like 2 week turnarounds. If you find a cast wheel you like, you could have them on this afternoon.

and I was also looking to get a 5th wheel since the srt8 doesnt come with a spare wheel if I got it the size of the front wheel would it fit the rear?

I got a custom offset (nearly flush with the fender) on my BMW. I chose a custom powdercoat for the face and polished lip (which they do by hand) and I waited 4 weeks plus delivery. There is something to be said though for "bespoke" wheels, that is, completely custom. I would bet price without tires for 20's to be in the 4-5K range. Mine were $3800 for 19X8.5 & 19X9.5
You have to be patient for this type of work. Cast wheels are fine too if you can find proper offsets et al.
Good Luck

Here are the wheels I had made for my truck. They are 20 inch Forgeline 3 piece aluminun alloys. Forgeline can make them in 22 inch also. They run a little over a thousand a piece and took about five weeks to have made and sent. Check their website at Forgeline.com
http://i168.photobucket.com/albums/u178/laddcruz/Newwheelsjeep004.jpg

I have dvinci 22's look in the member gallery. its a red rock jeep on black 22's

just put wheel addapters and go with the LAND ROVER bolt pattern and u got thousands of top manufacturer's .thats what i did . way more options lots of rims with lips 24"s etc.Its a bigger dollar market.3/4 inch aluminum wheel adapters.

I don't have an SRT8 YET, but I painted my rims. I have a black 00WJ.. I just put my car on blocks and had a local powder coater strip my stock rims and powder them black. It's a VERY cheap option.. If you like the stock rims, but want black, this is the best way to go