33's on an '04 Rubicon

I'd like to put 33" tires on a 2004 Rubicon (automatic trans with 4.10 stock gearing). Got stock 16" wheels and 35" tires now (Rancho Rock Crawler Competition lift, too tall for stock gearing, too hard riding, etc.) Looking for ride quality offroad (east coast, rocks, roots, ruts and a bad back). How much better would load range C 15" tires/wheels ride than load range D 16" tires/stock wheels ride (none, some, good, great)? I'd like the BFG KM's on the Jeep and would like to stick with that tire (lots of mud too).

Thanks!  

That would be an excellent choice of tire! The Load Range C tire will have a softer sidewall than the D which will really help with ride comfort. You'll like them.  
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99% of your ride quality is your suspension setup. Tire changes will give you a little smoothness and refinement on smooth road surfaces but will do very little to soften up a rough ride where the road surface isn't perfect.

Bigger, heavier tires should have a little stiffer suspension (springs and shocks) just to control the added un-sprung weight of the wheel and tire combo.

If you changed from a load range of D to C and dropped from a 35" to a 33" and the tread pattern stayed the same, you probably would not notice any improvement in overall ride quality. But that would be hard to do because you probably wouldn't be able to find a tire that comes in the same tread and two different load ranges that close in size. So most likely you would be switching brands and tread patterns and that does make a difference in ride quality. These differences would be most obvious by switching from a mud tire to a great riding all-terrain. Switching from one quality mud tire to another quality mud tire would be a subtle difference at best. But again, if your suspension setup is not "soft" , you still won't get a soft ride.

You can make a huge difference in ride quality by changing your suspension setup. Springs and shocks make a big difference. Also, control arm angle and control arm bushing material make a big difference. Tire size and certainly load range changes are not going to give you what you are looking for.

What tires are you running now and how much suspension lift do you have?  

Thanks, good info.

The Rancho Rock Crawler for a Rubicon lists a 2.5" lift which I assume is on top of the Rubicon's higher lift than a standard TJ. All totaled it's pretty high (4.5" total I think). The springs are stiff. Rancho's technical helpline said they are necessary for the weight of the Jeep (hardtop, winch, Warn bumbers) but I did the math and the total GVW with all that stuff is still within what the STOCK suspension is rated for. Even with the shocks set on the lower setting (like 2 out of 7) it beats me up offroad, so the springs seem to be the culprit. On the lower shock damping settings the Jeep really wallows the street.

My goal is to lower the Jeep as much as possible to clear 33" tires and stick with BFG K2 MTs (they work great in East TN mud) and they are available in 33" heights in both 15" (load range C) and 16" (light truck load range D and E) sizes. Thinking of going back to stock springs with JKS coil spring spacers so I can preload the front to account for the winch (Warn 9.5 ti).

So my original question was a cheapass approach to: 1) change tires and see how much it helps; 2) if necessary take off the Rancho Rock Crawler kit and go back to stock springs with coil spring spacers and a more compliant shock (length and manufacturer to be determined).

Suggestions appreciated!