According to tirerack.com this was the stock size on the Srt10 22's. Think it will fit the 4th gen without rubbing? I plan on swapping my Srt10 replica 20's for the same in a 22!

 

I'm running 305/45/22 on my SRT10 Replicas. I would run this size rather than the 305/40/22. The 45 series is slightly narrower and taller than the 40 series. At full lock, my tires just touch the upper control arm, but nothing to worry about. With the 40 series being a bit wider, you may have issues. This is on my stock height 4x4. Yours is lowered so you may have different clearances.

 

that is my concern as well. Tire rack.com recommends a 285/45/22, would that fit better?

 

A 285/45/22 should fit with no issues at all.

 

For height you'll be fine as stock 275/60/20 are 32.9 inches and 305/40/22 are 31.6 inches but the width ya id look into it..
Id go 285/45/22 which is the stock size of the 2011 R/T Forged wheels
You know they will fit if they are OEM size takes the guessing out of it.

 

A 305/45 should be 30mm (aprox 1 inch) taller and exactly the same width as a 305/40... assuming that the manufacturer is labeling them right. Doesn't always happen though.

 

I am running 305-45-22 rear and 285-45-22 front.

 

He is a 4x4 though so he has to keep the same tire ratio's all around or else in 4x4 mode diff's or more likely transfer case will grenade

 

I'm running the 305-40's all around, I do notice a bit of a rub on when I turn all the way over left or right. Doesn't bother me and has not had any effect on the tires. I normally don't go all the way over so rarely is it an issue. I might consider the 45's for next time. I know some are using spacers so that would be an option, as well.

 

i have a 3/5 lowered 2009 4x4 rcsb .when i got my rims/tires i went with 305-40-22 they were soo close when puton all it took was a little drive down teh road to realize they were rubbing. rubbed a nice gouge about 1/8 inch into the tire all the way around. luckily they were "test fit" by a local tire shop and they bit the bullet on this and ordered me new tires free of charge. i went with 285-45-22s all around this time and they fit great... ( when i went back i looked at a few diferent 305mm tires and they all measured different. werent all a true 305mm wide. with a 1/4 spacer a 305 will be fine.... not sure of the backspacing of the rims you have but my kmc slides are 15mm (stock 20s i believe are a 19mm) so in theory yeah a 305 will fit as long as the 305 tire you look at is eaxactly 305mm wide...