Home Forums Gear Hunting Trucks and Four-Wheel Drives Tried 17 inch rims and tires today!!

I have a 2007 Dodge Ram 1500 Quad Cab SLT 4x4, Hemi, auto tranny, 3:92 gears/limited slip diff, 20 inch wheels.

I put my parents 245/70-17 rims and tires from their 06 Durango on my Ram today. I didn't want to give them back. It felt like a different truck!

It drove, rode, stopped, steered, took off, handled, it did everything better then it does with the 275/60-20 rims and tires.

I can't spin my tires on dry pavement with my 275/60-20's. If I'm at a dead stop and floor the gas peddle, I'll get a chirp or two and the truck takes off, pretty well. With my parents 245/70-17's, from a dead stop I floored it, blew the tires away, left two 10 to 12 foot long stripes as the truck launched like it never has before. I was amazed. That being said, I don't regularly try to spin my tires. I just wanted to see if the smaller tires would be more responsive and my father knew what I was going to do to, so it was all good!

I was driving on the interstate with the cruise set at 70 MPH (speed limit was 65 MPH). I caught up to a car and had to pass it. I floored the gas, the truck down shifted two gears, one then two....that quick. It pulled very hard to about 85 MPH as I flew by the car and let off. Again, I was amazed. I don't know how fast I was really going because my truck is calibrated for the 275/60-20's. When the cruise was set at 70 MPG, only one car passed me. I passed a few vehicles, but was going with the flow of traffic for the most part.

When I turned at slow speeds, it felt like my LSD was actually working. In other words, If I turned left, I could feel and hear the drivers side rear tire wanting to break lose. The same if I turned right, I could feel and hear the passenger side rear tire wanting to break lose. Every other vehicle (car, trucks/SUV) I've ever had with a LSD did this. Today was the first time I felt this with my truck.

It stopped better. Handled better. It didn't follow the crown of the road on the interstate or bounce around on bumps like my 275/60-20's do.

I'm definitely going to buy 17 inch rims (most likely aluminum). I don't know if I want to go with 245/70-17 or 265/70-17 tires. The 245's are 30.6 inches tall. The 265's are 31.7 inches tall. I really want to see how much better the 17's will pull my trailer though!

Big wheels make no sense on a rig that sees any offroad at all. You really need some sidewall to make offroad tires work properly. I just dont understand the 18,20,22" craze. I prefer 16" wheels if they fit, 17" is still ok with 32"+ tires.

The reason your truck felt like a different truck was because you essentially changed your gear ratio from 3:92's to something in the 4's. a lower gear ration will get the tires spinning faster and give you a better accelleration as well.
You never know, you might even increase you mpg's depending on how the engine is cammed and a myriad of other things.

To tell you the truth, I think the 20's change it from 3:92's to lower 3's. I've always' thought the 20's were to big for the truck. They're also extremely heavy compared to the 17's.

If they changed to the lower 3's you would have less resposne and a lower "cruising" rpm, like on the highway. Tom 264 is right, it is probably in the 4's.

Most likely your milage will decrease, but not to the point where you would notice something signifigant.

Tom

The ability to have more sidewall flex makes all the difference in the ride!!!

What size rims and tires did that truck come from the factory with?
If it came with 20' rims then I would be correct in the fact it would change the gear ratio in the low 4's but if your truck came from the factory with something like 17" rims then yes you would be correct in that it would change the gear ratio in the mid to low 3's by going to the 20" rims.
And weight is a contributing factor as well, I used to have magnesium rims on one of my older muscle cars when I was younger and I swear that they were the greatest/cheapest horsepower secret I ever had on that car.

I understand what you guys are saying. However the only way to change the gear ratio is to change the ring and pinion gears. My truck came from the factory with 275/60-20's and 3:92 gears. It has 47 teeth on the ring gear and 12 teeth on the pinion gear. As do trucks that come with 245/70-17's and 3:92 gears. The ring and pinion gear ratio doesn't change by changing the tire size. 47 divided by 12 is 3.916 (3:92) anyway you look at it.

The reason I feel the 20 inch tires and rims give me the "perceived" feel of 3:23 or 3:42's is because the standard size tire on a Dodge Ram 1500 4x4 is 245/70-17. I've been in a few with that size tire and 3:92 gears. They felt like mine did when I put the smaller tires on....which was AWESOME! Now that I put the 20's back on my truck, it feels lethargic. .

One of my friends has a Ram like mine with the Hemi, 3:55 gears and 245/70-17's. His truck pulls a little harder then mine and he has less gear. Another friend has the same truck as mine, Hemi, 3:92 gears with 245/70-17's. His truck pulls a lot harder then mine does. He gets better mileage too. That's why I feel the 20's give the "perceived" feel of knocking the gear ratio down and the standard size 17's feel like 3:92's.

At any rate I appreciate all the feed back. I also have no idea why Dodge would put the 20's inch wheels on half ton Rams. So far that's the only thing I don't like about my truck. I'm looking for a good set of used 17" aluminum rims now!

What do you guys think of the Goodyear Wrangler SilentArmor tires? I need a good all round tire. One that's really good in the snow. Thanks guys!

It could be a weight issue too. Those 17's might just be that much lighter. Sometime it makes a big difference.

I have had horrible luck with Goodyear tires of several styles on several different vehicles.

I like Firestone Dueller Revo's and BFG All Terrains. The Firestones will run you near $700, the BFG's will be $800+. Those are the only two I have bought in the last 10 years of truck ownership.

The difference is in the tire diameter. Tire diameter, transmission gearing, and rearend gearing all add into the equation. You probably went from something like a 33" tire to a 31.5" tire effectively changing your overall gear ratio.

I did the opposite on my 04 Ram when I went to a 35" tall tire. Mine rode a ton smoother but had less takeoff power. Funny thing was I think it actually pulled my boat better with the taller tires. I guess it put the engine in a sweeter RPM range.

He went from a 33" tall tire to a 30.5" tall tire. You're right, he effectively changed to a lower (numerically higher)gear ratio. If he had 3.92s before he effectively has 4.24s now.

Thats what I was trying to tell him.

I was talking ring and pinion gear ratio in my front and rear differentials. That doesn't change by changing the tire size. I have no idea what the overall (tranny gear ratio, differential gear ratio combined with tire diameter) ratio is.

You guys are talking past each other. What ring and pinion the differential has in it is different than effective gear ration whioch is the consideration of tire dioameter, ring and pinion ratio and tranny drive ratio. Taller tires will give a taller effective ratio, shorter tires a deeper ratio.

Planemech, like I said in my last post, I thought we were talking ring and pinion gear ratio. I have no idea what the effective/overall/final ratio (tranny gear ratio, differential gear ratio and tire diameter combined) is. I wouldn't even know where to begin to try to calculate it.

Yes the 17's are A LOT lighter then the 20's. I know one guy that took his 20's off (33" tall w/ 633 revs per mile) and put 17's on with 275/70-17 tires (32.2" tall w/ 645 revs per mile) and he said his performance picked up a lot and he gained a little bit better MPG as well. The tire diameters are very close. He seems to think it's because the 17's weigh a lot less.

I've had good luck with Goodyear and haven't been real crazy with Firestone, although I'd be willing to check them out. I'll definitely check out the BFG All Terrains though.

So what you're saying is you don't buy your own tires!

I figured I try them before I bought them!

Gear ratio is simply the number of times the shaft turns for each revolution of the tire (since the tire revolves at the same rpm as the ring gear). If it turns exactly 4 times, you have a gear ratio of 4.00. What matters is how far the truck moves for each rev of the tires and that equals the circumference of the tire. A 30" tire will move 94.2" for each rev. A 33" tire will move 103.6" which is 10% farther. It's more difficult to say how that affects power because there are lots of variables in the engine setup.