IT all depends on your intent for the truck. If you want it to be a street truck, then go with the larger wheels. Then you can put on a performance tire with a shorter sidewall that will give you better handling. Also, if using an alloy rim or aluminum rim then your overall unsrpung weight will probably decrease, further increasing your truck's handling.

If its gunna be an offroad truck then generally the 17's are better. First, like what others have said, tires are generally cheaper. Second, when you put a larger tire on the smaller rim you get a larger sidewall. This is good for offroading because when you air down the tire the larger sidewall allows the tire to deform more around objects ( i.e. rocks) to give better traction. Plus this larger sidewall serves to protect the rim from scuffing (like from curbs).

In the end its your choice, but those are the basic performance properties of each choice. (And i know there are exceptions to everything i said and i'm sure there is someone out there dying to let me know it, but like i said these are the basic ideas behind each wheel selection.)

 

Well the 2009 charts had a 1,000 lb difference between the 17's and 20's. The new charts numbers have been dramatically increased, but no longer show a big difference between the two wheel sizes.

I'm sure there was a reason they chose to differentiate the two sizes in the 2009 charts. I'm theorizing that whatever the original difference was that prompted them to have two sets of numbers is still a relevant scientific factor. (Other truck makers seperate capacity specs by wheel size also) But dodge obviously changed their ratings to numbers that are very similar now. I suspect that they either artifically increased the tow ratings of the 20" wheels beyond the recommended safe limits, or played conservative with the numbers on the 17's. I would say the latter is more likely, but who knows.

Another possibility could be that 2010 rams equipped with 20" wheels come with different tires that the 2009 models.

 

I agree usp45compact, Dodge did have different towing specs in 09. From what I have researched so far is that after further tests, Dodge's engineers have concluded that the 4th generation Rams are better then they had previously believed.

To be honest, I don't know what to believe about tow ratings anymore. Every person I have talked to at Dodge and at shops that sell tires look at me like I have 3 heads when I mention any difference in tow capacity because of tire size. The only mention of a difference I have found is from the online community.

I am of the belief that if nothing has changed from an engineering standpoint on the 2010 Ram over my 2009 Ram and they increased the towing capacity of the 2010, then my truck should be able to tow the same amount whether they retroactively "certify" it or not.

It all gives me a headache.

 

I think the lower tow rating had more to do with the lifetime warranty that was still availible on the 09's. Like most warranties the more exclusions they can put out there the better for them. If most people follow Dodge's reccomended weight limits it will equate to less repairs down the road on the driveline. There is no way a 3 gen could pull more then a 4th. The 4th has more power and torque. It should be atleast the same. I know the 4th gen has the coils but between air bags and w/d you could accomplish the task. My 05 D was rated to tow 9000 lbs... and 09 Ram can't do the same? Come on!!!

 

If the diameter is the same, you get a smoother ride with the 17's, more side wall. Low profile is better cornering performance but you feel more of the road. Larger diameter is loss of performance, that's a fact, just dyno both and you will see the difference.

 

How does one know something like that, for instance maybe all the 20" get 392 gears stock, no choice unless youwanna go 411 or 456..would be nice.
Maybe they put a slightly stronger spring, that might be all how would you know that engineering info, that would not be in the literature that we see?

 

I switched my factory steel 17's out for the 20" factory Chrome Clads. I am a "performance minded" individual who would easily agree to sacrifice gas mileage or comfort for performance - however I do not "feel" any difference at all with the larger diameter wheels.

The tires on the wheels are also the factory tires (Goodyear something or anothers) and there is PLENTY of sidewall left. As such, there is - in my opinion - no difference what so ever in ride quality. Gas mileage sucks with either the 17's or the 20's, so there wasn't anything to complain about there either.

As for handling - I personally think the truck handles great (for a truck anyway). This is by far the best handling truck I have ever owned. The switch to 20's didn't improve the handling or make it worst. It's just the same as before.

If you research the tire sites you will find that the factory tire size for the 20's is just slightly taller than the stock 17's - and I do mean slightly. As such, the speedometer is now slighty off. This "issue" will be corrected when I wear out the current tires and replace with new ones. I'll simply buy a tire that more closely matches the height of the original tires. In my case I got a great combo deal from the original owner of the wheels and tires and saw no need to drop an additional $600 or more to replace the tires at that time. I had originally offered the seller a reduced price for the wheels alone - which he accepted - but then I decided at the last minute to go ahead and buy the tires as well.

If I had it to do over again I would not change a thing. I really like the look of the truck with the Chrome Clads.

 

I know because Dodge is saying that they did not make any changes to the 2010 engineering wise. The increased the towing capacity of the Dodge Ram from 2009 to 2010 from 9,100 lbs to 10,450 without changing a thing. Their reasoning is that after more testing they found the truck can tow more than they thought originally. Google "2010 Ram towing capacity" and you will see what I am talking about. It's on EVERY review of the new Ram.

 

Dude pay the dealership 40 bucks for a reflash. Or get a tuner if you are truly performance orientated.

 

Dude - it's a truck. I use it to haul stuff. As such, I don't care if the speedometer is slightly off as it has zero affect on the prerformance to begin with.