Problems that arise from tire size upgrade questions.

[ZLAYER]

I have a 19 PW and am in the “should I go 35s or 37s phase”. As per usual I’m concerned about mpg with 37s and loss of acceleration. I drove a Jeep (which have no power to begin with) with 37s and I was unacceptably a weak. I know the PW would not be as bad, but it’s still a concern. Any body use the pedal commander to alleviate any sluggishness, and does it pay off?
But my main question is with recalibration of the speedometer/odometer/shift points, which is usually solved with something like the AEV procal, but it is not compatible with ‘19 trucks. What are ‘19 owner doing to fix this?

 

[olyelr]

You could go with a TazerRAM for recalibration.

If you go 35’s or 37’s you should definitely expect to notice negative performance as far as taking off and stopping goes. Regearing and better brakes are options to remedy this, but obviously quite costly. Weather or not it will be acceptable if you do nothing really depends... some people swear they hardly even notice a difference, other say it is very noticeable. Its personal opinion, IMO.

With the 8 speed, however, I really do believe it wont be as noticeable as with the 6 speed. That will make a world of difference I think.

And as far as mpg’s go, its a crap chute. Simple fact is these trucks drink a lot no matter what. Installing larger, heavier tires with less rolling resistance sure as hell cant help.

 

[ZLAYER]

I should clarify that I’m not looking for a solution to the mpg thing. I know that’s part of the territory. As for the power thing, I also know that’s part of the deal, but I was just wanting feedback from anyone who has specifically used the pedal commander and did it restore anything close to a “back to stock acceleration feel”?

And thanks, I’ll research the TazerRam.

 

[Grand Mesa]

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[Maligator]

I heard a comparison the other day that said having 35s drives like having 4 people in the truck and 37s drives like your constantly pulling 1500lb trailer all day.

I would concur with this, I have some power loss and some extra downshifting but nothing that would prevent me from running my 37s . I used to run my 1500 with 37s and 3.21 gears so I really don't notice this much at all


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[olyelr]

I heard a comparison the other day that said having 35s drives like having 4 people in the truck and 37s drives like your constantly pulling 1500lb trailer all day.

I would concur with this, I have some power loss and some extra downshifting but nothing that would prevent me from running my 37s . I used to run my 1500 with 37s and 3.21 gears so I really don't notice this much at all


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I completely agree... good analogy. I cant vouch for the 37’s, but with heavy 35’s I certainly noticed it. The truck felt slow and almost underpowered to me in factory form, so the 35’s certainly didnt help it any.

 

[ZLAYER]

It’s sounding more and more like stock tires are for me then. 1st world problems. Blah!

 

[Blue Streak]

After putting 37s on my '17 there was a noticeable performance loss, not drastic but it was there. Mileage took a hit in town but improved on the freeway. I added cat back exhaust and a Peddle Commander. The difference with those two alone I feel brought it back to where it was but the truck still down shifts a lot on small hills. The truck goes in next week for 5.13 gears. This should make a world of difference!

 

[olyelr]

After putting 37s on my '17 there was a noticeable performance loss, not drastic but it was there. Mileage took a hit in town but improved on the freeway. I added cat back exhaust and a Peddle Commander. The difference with those two alone I feel brought it back to where it was but the truck still down shifts a lot on small hills. The truck goes in next week for 5.13 gears. This should make a world of difference!

keep us updated.... somewhere.... i so bad want to do this!

 

[Maligator]

I completely agree... good analogy. I cant vouch for the 37’s, but with heavy 35’s I certainly noticed it. The truck felt slow and almost underpowered to me in factory form, so the 35’s certainly didnt help it any.

I really didn't notice a world of difference from stock to my 35s. But I do notice my 37s, doesn't bother me in the least though

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[Rick Ram-jet]

I heard a comparison the other day that said having 35s drives like having 4 people in the truck and 37s drives like your constantly pulling 1500lb trailer all day.

I would concur with this, I have some power loss and some extra downshifting but nothing that would prevent me from running my 37s . I used to run my 1500 with 37s and 3.21 gears so I really don't notice this much at all


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I think this is a good way of putting it! You will notice 35`s but get used to it pretty quickly, 37`s are much more noticeable.
Since you have a power wagon (I assume 17in rims and stock suspension) go for the 35`s, they will be the best all around choice and you should have plenty of sidewall for four wheeling. The only reason I changed rims and tires (to 17in w/37`s) is 35`s on the stock 20in rims have a too short sidewall for off-roading, imo. Btw, 37`s on stock 20`s would have rubbed too much on the inside wheel-well/radius arms, etc.
Changing settings on my pedal commander (more sensitive) for the most part negated the extra weight/height of the larger tires....

 

[ZLAYER]

Good stuff guys. Pedal commander sounds like a pretty worthwhile investment. I’m seeing some good reviews on the rough country speedometer calibrator, and it apparently works on ‘19s.

 

[MarshRam]

I cant comment on what is out there right now to calibrate your tires for a 19. I can say, 35's or 37's, chances are good say goodbye to your MPG, varying losses depending on variables!. As for "feeling sluggish", more variables.

I have a 2012 single cab ST 6 spd with 4.10 gears with just about all the bolt on performance mods you can put in it, Jay Greene tune + a valve body. Lose control of the backend if I am not careful. I also have a 6" lifted crew cab SLT 8 speed with moderate bolt on mods (canned diablo tune), standard 3.21 gears, extremely heavy fuel vapor rims coated with hydrodip + 35" MT's. I never lose control of the ass end in that truck unless the roads are wet and PC is set to the max, but I swear they both "feel" just as fast as one another. Have a pedal commander in the lifted SLT and throttle tuned on the lowered ST. It's obviously impossible my lifted SLT is faster than my ST, but they sure do "feel" damn near the same. Point is, I think you can do some additional moderate modding to find your happy place.

As for the pedal commander, No HP gain, but a great mod to get a faster throttle response and "feel" like you are gaining much more than you actually are. My wife ******* about how much her new Honda Accord was slower than her old one. Same engine and she was right about its responsiveness, Pedal Commander changed that perception real quick! Lol.

 

[JohnnyMac]

I put 35's on my 6.4 with a 6-speed transmission (2014). Felt a difference. Tuned it with a Diablo that has options similar to the PC and it fixed it right up. I have a PC on my EcoDiesel (with 35's) now and it's pretty much awesomness in a box.

 

[Grand Mesa]

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[ZLAYER]

Lol. The police would be busy around here!
I see at least 5-10 trucks/ jeeps everyday with 37+ tires, so it’s not something I’d be worried about.

Unfortunately, Tennessee is one of those handful of states which has both frame and bumper height restrictions. Police sirens! Pull over. Those 37" tires just might put your PW over the legal limit.

http://www.liftlaws.com/index.htm

 

[62Blazer]

When it comes to larger tires in repards to performance and MPG losses, it's not only the increased size and leverage issues but also the increased weight typical with bigger tires. Rolling mass plays a much larger factor than static mass, meaning it takes more "power" to spin weight than just move it down the road. Adding 20 lbs. per tire and wheel combo for 80 lbs. total will cause some performance and MPG losses but simply throwing 80 lbs. of weight in the bed would never be noticed. Now I'm not saying that increasing the tire and wheel weight by 20 lbs. per corner makes it undriveable or even causes a huge issue, but if you did true recorded acceleration, braking, and MPG runs you would see a difference in the numbers.

The other thing to consider is that if you do NOT recalibrate the speedometer it will hurt the performance and MPG more. For MPG calculations with no speedo calibration the larger tires will mean you are actually travelling more miles than what the odometer shows.......if the speedo is off so is the odometer..... For example, going from the stock 33" to 37" tires means the speedo and odo will show 12% lower. This means when calculating fuel mileage the odometer will say you went 200 miles but you actually went 224 miles. If you put 15 gallons of fuel in the tank and do the math using 200 miles means 13.3 MPG, where as if you used 224 miles that means 14.9 MPG. The display on the truck will have similar issues, and in the end meaning you are getting better MPG than what you think. On the performance side, having incorrect speedo readings can affect the shift points, torque management, and other aspects of the truck.

 

[Vicman]

16 PW here with 35 STTs. I had the dealer re-cal the speedo. No pedal commander, I think I would have too much trouble not romping it all the time. I noticed 2-3 mpg drop on hwy (don't go over 70 or it's more like 5-6) not much difference kicking around town or in the woods. Very and I mean very little drop in felt power. It takes off as fast as I really want and will still turn the tire over on dry pavement with trac control on. No difference with a big load or towing.

 

[Flea]

I put 35s on mine and my speedo seems to match my gps ?

 

[Rated R]

I put 35s on mine and my speedo seems to match my gps ?

The error will increase the faster you go.