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Lance M · 03-21-2015, 08:07 PM

Whatever makes you feel the safest and most comfortable.
However, you have basically the same truck as BoldAdventure and I do. A few differences, but not huge differences and mine is rated to tow 8,700lbs. If I had a Hemi, My tow rating would be over 10,000lbs. I have 20" wheels and GoodYear Wrangler SRA P275/60/20 tires. The 20" wheels and tires are not the issue.

jhawk40 · 03-21-2015, 08:35 PM

I will weight in on this. I have a 2014 Ram 1500 with Hemi but before that I had a 2005 Ram with a Hemi. The 2005 had 20" wheels when I bought it and kept them until I needed new tires then changed to 17" wheels. I have a 79 31' excella GVW 8550. While the 20" pulled ok after changing to 17" wheels it seemed to not struggle as much up hills and even increased my gas millage while towing by about .5 mpg. I was pleased enough that when I purchased the 2014 I had the dealer change the wheels to 17" YMMV.

Boxite · 03-21-2015, 09:27 PM

The smaller 17" wheels/tires will behave similarly to dropping down a gear....they will pull better than the 20's. Ram tells it like it is... :wink:

cwf · 03-21-2015, 10:09 PM

I think we may be saying 'similar' things... The 20's vs the 17's will change the gearing ratio...right? So..Ram says.. the 17's let you 'tow' more... not 'carry' more... big difference.. as Gahorn said above.

BoldAdventure · 03-22-2015, 07:17 AM

It's because of the decrease in rotational mass. The 17's won't handle the same as the 20's but you're probably already not taking tight turns fast in a truck anyways.

SteveH · 03-22-2015, 07:56 AM

The final gear ratio will not change with a tire and wheel change unless the overall diameter, or really more important, the circumference of the tire changes. Has to do with revolutions per mile.

So, what I'm saying is, if you have a 30" diameter 20" tire, a 30" diameter 17" tire will result in the same final gear ratio. However, weight capacity may go up....depends on the two tires.

Lance M · 03-22-2015, 08:25 AM

This is for a 2014 RAM 1500, but I'm pretty sure that 2009 is very similar.
20" wheels come with P275/60/20 tires that are 33"
17" wheels come with P or LT 265/70/17 tires that are 31.7"

It is a change in effective gear ratio, but not very much. Maybe 150 RPM at 60 MPH.
The LT245/70/17 would give the lowest effective gear ratio with about a 200RPM at 60MPH.

The following are tire sizes that are pre-programed in the PCM for speedo calibration-

235/80/17 31.8"
245/70/17 30.6"
265/70/17 31.7"
275/60/20 33"
285/45/22 32"

Jukeboxfun · 03-22-2015, 08:56 AM

Quote:

Originally Posted by Top

This is for a 2014 RAM 1500, but I'm pretty sure that 2009 is very similar.
20" wheels come with P275/60/20 tires that are 33"
17" wheels come with P or LT 265/70/17 tires that are 31.7"

It is a change in effective gear ratio, but not very much. Maybe 150 RPM at 60 MPH.
The LT245/70/17 would give the lowest effective gear ratio with about a 200RPM at 60MPH.

The following are tire sizes that are pre-programed in the PCM for speedo calibration-

235/80/17 31.8"
245/70/17 30.6"
265/70/17 31.7"
275/60/20 33"
285/45/22 32"

Do you mean the tire size is user adjustable in the truck's heads up computer display? That would be nice.

J. Morgan · 03-22-2015, 09:34 AM

Quote:

Originally Posted by Top

This is for a 2014 RAM 1500, but I'm pretty sure that 2009 is very similar.

20" wheels come with P275/60/20 tires that are 33"

17" wheels come with P or LT 265/70/17 tires that are 31.7"

It is a change in effective gear ratio, but not very much. Maybe 150 RPM at 60 MPH.

The LT245/70/17 would give the lowest effective gear ratio with about a 200RPM at 60MPH.

The following are tire sizes that are pre-programed in the PCM for speedo calibration-

235/80/17 31.8"

245/70/17 30.6"

265/70/17 31.7"

275/60/20 33"

285/45/22 32"

The difference between the tall and the short is about 6% in distance traveled per wheel revolution.

This change can effectively (about the same as) change 3.55 gears to 3.73s...

Fairly significant. But...

If we assume a 2,000 Rpm baseline at 60 mph, this will affect only about a 120 rpm increase.

But still, a six percentage difference at the wheels also equates in an effective increase in leverage at the crank journal..... Thereby increasing the effective torque of the engine by six percent (at full power in a given gear) six percent "net" is kinda a big deal.

1/2 Ton 4WD Truck, 72 Sovereign Hensley Arrow

xrvr · 03-22-2015, 10:00 AM

Yes I thought about what I said. Twenty inch wheels designed for cars have no place on a tow vehicle. Twenty inch truck tires are different. Not sure the op new the difference, so my comments. Twenty two and a half mh and truck wheels are entirely different. Some AS wheels are rated at only 65 psi. You can check on the backside of the wheel. So if you buy LT. tires and inflate them to 70-80 pounds you could be in trouble. The new sixteen inch wheels people blowing money on are okay. Also when I had my Interstae I was looking at custom wheels. Almost all had too low of a weight rating. The best I found were the ones Dodge and MB sold, standard equipment now I think. No I don't have proof of this, just experience. Not an expert as some on here appear to be. My two cents, take it or leave it. Jim ready for the comebacks.

Lance M · 03-22-2015, 10:15 AM

Quote:

Originally Posted by Jukeboxfun

Do you mean the tire size is user adjustable in the truck's heads up computer display? That would be nice.

You have to have the PCM settings changed at the dealer.

Not user changeable.

SteveH · 03-22-2015, 10:18 AM

Yes, going from 33" to 30.6" tires will make a noticeable difference.

If you don't believe this, try going from 30.6" to 33" tires. More "noticeable" in that direction.

J. Morgan · 03-22-2015, 10:27 AM

Quote:

Originally Posted by zigzagguzzi

Yes I thought about what I said. Twenty inch wheels designed for cars have no place on a tow vehicle. Twenty inch truck tires are different. My two cents, take it or leave it. Jim ready for the comebacks.

I was going to post in your defense earlier Jim but I got distracted.

What I was going to say is that CONTEXT IS IMPORTANT, and clearly the context you were speaking WAS NOT semi wheels.

It bugs me when people pull simple words out of context for the sake of ridicule.

It is too hard and too cumbersome to try to have a conversation when context can not be assumed to one degree or another.

Reasonably intelligent folks can usually see context and address in kind in a proper context, unfortunately many otherwise intelligent folks think that a person not crossing all of their contextual "Ts" and dotting all of the contextual "I's" is an invitation for mockery.

This kind of thinking, and the fear of mockery it generates lead to long monotonous, boring, and insuccinct posts that no one will read...

Just sayin...

1/2 Ton 4WD Truck, 72 Sovereign Hensley Arrow

SteveH · 03-22-2015, 11:18 AM

FWIW, I had a 1/2 ton GMC with 20" wheels and of course tires, and we towed with it for about a year and a half. First a 23' and then a 25' Airstreams. I thought the 20 inchers were great. Very stable in all types of driving, but did not deliver a luxury car ride.

I tried them on my 3/4 ton Ram when I was chasing a stability problem, and although they were pretty good, I got some bad reports on the tires I had (Goodyear Wranglers), so got rid of them and went to 18" Michelins. Yes, I've spent way too much money getting this Ram to tow the way I wanted, and the fact is the only problem with it was my ignorance.....the motor is heavy and therefore the front tires need as much air pressure as the rear! Duh!

Boxite · 03-22-2015, 02:15 PM

Geesus-Keereist! Is this horse dead yet?

Did the Ram chart say anything about "LT" or "P" rated tires? NO!
...and that's because that is not a major factor in towing capacity. (It IS a factor in carrying/weight capacity and in sidewall rigidity...but has little to do with towing weights.)

Tire sizes affect tire HEIGHT... or overall diameter, and that's the difference in towing capacity...all other things being equal.

paiceman · 03-22-2015, 02:29 PM

There are several factors I look at when buying a two vehicle. Time rating, I use E only and quite frankly don't really care about 17" - 18" or 20". I have 20s on our F350 now, love them, very stable side to side with lower sidewall. Then I look at load carrying ability of my TV - ie payload. Then, not in order I look at towing capacity of the TV. And that is pretty much it.

I don't like Dodge, Ford guy only but that is neither here nor there. A 1/2 Ton in any of the four offered will do the job. Just watch your payload - you, your significant other and ANYTHING else you put in the truck including the hitch weight. Check to make sure the tires are E rated and if you can't afford a new TV, don't get one, use the 09 until she drops, which hopefully is not for years to come. Drive under 65 if you are running ST tires on the trailer and in my opinion you'll be fine - note opinion, but then I change vehicles like many people change pants so I've done this many - many times and each time I get to teach the Ford sales people something.

Stop worrying and enjoy.

Jukeboxfun · 03-22-2015, 03:41 PM

I talked to my father in law. He is 82 and has owned several travel trailers through the years including 5th wheel and a Class A motorhome. In his younger years he was a tractor trailer driver and ran his own filling station and auto repair.

I explained my dilemma and he asked if I was going to use a weight distribution hitch. After I told him I was, his advice was to not get new tires or change anything on the truck until I have towed the trailer some. He advised that the engine and horsepower are more than adequate. Then later I can decide to just get new tires the same size or go with the smaller wheels and tires.

Similar to some advice I received in this thread. So I think I'll try what he said.

Al and Missy · 03-22-2015, 04:04 PM

I think you are on the right track. According to Ford, the trailer towing capacity of my F150 increased 450# going from 18" to 16" wheels. It is as several others have said. It effectively lowers the rear end drive ratio and gives you more torque at the wheels for a given engine rpm. The down side is less fuel mileage at the same speed.

The best way to do it as your FIL suggests. Get a good WD hitch, get it set up right, (I'd add get weighed to ensure you are within the limits for your truck), and get out there and try it. While many have suggested that my F150 should have towed my trailer fine, it had difficulty (read lost power and had to cool off before proceeding) on a 6-mile 8% grade. On the flat or on less challenging slopes, it was great. I ended up getting another truck, but if I were just going to be towing in flat country I would not have changed.

Al

BoldAdventure · 03-22-2015, 04:21 PM

When you have new people asking questions, context and facts are important.

Back peddling, mocking and calling people not intelligent enough to grasp context? What does that add to this thread? I asked for clarification, yet that was somehow mocking?

My experience tells me that the 20 inch wheels on trucks are designed and rated for the vehicle, they are not the same as car wheels. The p tires that are sold with my truck are also rated for my vehicle. Their load is adequate.

The FHWA wouldn't allow manufactures to sell vehicles with wheels that were dangerous or incapable of handling the load.

Are some better than others? Well that's a different question entirely now isn't it.

With a completely different context. Yes, stiffer sidewalls handle better when towing than thinner sidewalls.

But most people tow occasionally with their trucks, so the manufactures have all switched to better handling wheels and tires that provide better comfort and enough load rating for towing here and there.

BTW, sorry for pointing out your Burden of Proof fallacy. https://yourlogicalfallacyis.com/burden-of-proof

J. Morgan · 03-22-2015, 05:24 PM

I didn't say anything about the specifics of your position or Jim's position except that Jim was OBVIOUSLY not talking about semi wheels, AND that you brought up the semi wheels in attempt to mock him for no good reason, and it is true.

He in no way deserved to be ripped like you did. That was simply unjustified.

Further, if you want to talk about logic, how is it that semi wheels even entered the conversation about light duty trucks and trailers?

Apples and oranges.

In addition I never claimed that you or anyone posting here was not intelligent enough to grasp context, in fact, I am certain that you are plenty intelligent to grasp this but you posted rudely anyway.

1/2 Ton 4WD Truck, 72 Sovereign Hensley Arrow