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New Rims and Tires = VERY Sluggish... even with BB tune

agrats84

By agrats84
in Tires, Wheels & TPMS

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Zembonez Senior Enthusiast

Zembonez

Posted
Posted

the Cooper Zeon LTZ in 275/60R20 only weigh 47lbs. That ain't too bad.

 

 

That's not horrible but it is 6-7 pounds heavier than a same sized Michelin. A/T tires are pretty heavy. It's probably a good 10 pounds heavier than the 265-65-18s he had before and the 20 inch wheel is another 3-5 pounds over the 18 incher.

 

It makes a difference.

LilJuicedCoupe Enthusiast

LilJuicedCoupe

Posted
Posted

I know, it is what it is, but for an XL rated tire in that size the Cooper is a great choice even based on weight. A Nitto Terra Grappler is available in that size at a mere 42lbs but it's only "P" rated. That would be a great tire for reducing unsprung weight and still having a 33" tire. I may get those myself next time. (The factory issue Goodyears in P275/55R20 weigh 40lbs. I sure would like to know what all the various factory wheels weigh.)

 

Steve

kstruckcountry Senior Enthusiast

kstruckcountry

Posted
Posted

I didn't notice much difference between the stock 20's my truck had with Michelins when I drove it first and the factory 17's with the POS goodyear p ranges it has now, other than ride with the 17's is much better.

ShimanoFisherman Enthusiast

ShimanoFisherman

Posted
Posted

I have the Autocal so I never swapped out the PCM. I tried putting it back to stock and it feels no different. Maybe it is the tune and Justin can modify it. Hopefully that's the answer.

 

 

Did you have Justin tune the transmission? I could understand how just an engine tune might not be noticeable outside of WOT runs. But when you go between stock and tuned on the TCM, you should definitely feel a difference. Stock should feel like the transmission is full of mud as opposed to tuned which holds gears longer, shifts more firmly and should downshift more aggressively.

 

I know it is a night/day difference for me when I put it back on the stock TCM tune to take it in to the dealer.

agrats84 Enthusiast

agrats84

Posted
  • Author
Posted

I have the Autocal so I never swapped out the PCM. I tried putting it back to stock and it feels no different. Maybe it is the tune and Justin can modify it. Hopefully that's the answer.

 

 

Did you have Justin tune the transmission? I could understand how just an engine tune might not be noticeable outside of WOT runs. But when you go between stock and tuned on the TCM, you should definitely feel a difference. Stock should feel like the transmission is full of mud as opposed to tuned which holds gears longer, shifts more firmly and should downshift more aggressively.

 

I know it is a night/day difference for me when I put it back on the stock TCM tune to take it in to the dealer.

 

 

This is going to sound completely dumb and I should have known but- I should have also received a TCM tune from Justin as well as the ECM tune? I received the ECM tune from him, but not a TCM. I assumed that would account for the difference in tire size. I am running the same TCM that I have been running since he tuned me in June with my smaller tires.

 

Also, how can I tell what gearing I have? Is there a sticker or code somewhere? I thought I read somewhere its in the glovebox.

ShimanoFisherman Enthusiast

ShimanoFisherman

Posted
Posted

This is going to sound completely dumb and I should have known but- I should have also received a TCM tune from Justin as well as the ECM tune? I received the ECM tune from him, but not a TCM. I assumed that would account for the difference in tire size. I am running the same TCM that I have been running since he tuned me in June with my smaller tires.

 

 

I don't know how he does things now b/c I was one of the first ones to get an AutoCal, but you should have received four files. Stock PCM/TCM and Tuned PCM/TCM. He originally tuned mine in person so I had both already tuned and primarily use the AC to put the stock tune back in for trips to the dealer.

 

So if you already had yours tuned in person, I would think it would already have the Tuned TCM. But if you did everything remotely and you didn't explicitly load the tuned TCM file, then you're still on stock.

 

I don't know if the tire ratio change is made in the TCM or PCM.

NoMoreGM4Me Enthusiast

NoMoreGM4Me

Posted
Posted

This is going to sound completely dumb and I should have known but- I should have also received a TCM tune from Justin as well as the ECM tune? I received the ECM tune from him, but not a TCM. I assumed that would account for the difference in tire size. I am running the same TCM that I have been running since he tuned me in June with my smaller tires.

 

 

I don't know how he does things now b/c I was one of the first ones to get an AutoCal, but you should have received four files. Stock PCM/TCM and Tuned PCM/TCM. He originally tuned mine in person so I had both already tuned and primarily use the AC to put the stock tune back in for trips to the dealer.

 

So if you already had yours tuned in person, I would think it would already have the Tuned TCM. But if you did everything remotely and you didn't explicitly load the tuned TCM file, then you're still on stock.

 

I don't know if the tire ratio change is made in the TCM or PCM.

 

 

Just an FYI:

 

PCM = Powertrain control module (engine and transmission).

 

ECM = Engine control module.

 

TCM = Transmission control module.

 

Current trucks have a ECM and a TCM. Prior trucks they were combined and called a PCM.

rerla Enthusiast

rerla

Posted
Posted

Takes alot of wasted power to just spin those heavy things.

JackedBeaver Enthusiast

JackedBeaver

Posted
Posted

Agreed. When I put a 2" Rough Country level kit on my truck, along with 20" Incubus wheels and 305/50/20 Cooper Zeon LTZ's, my MPG and performance dropped like a rock immediately. Probably about 2-3 MPG and the performance is noticeable throughout the power band. Still thinking about going back to stock but not sure yet.

Gurrzt Enthusiast

Gurrzt

Posted
Posted

I wouldn't blame the tire size for the sluggish performance, there isn't enough size difference between the old and new for that.

 

 

+1 on that, I would blame a bad tune before I would even consider the wheels and tires (which I believe is a non factor).

jdubub Senior Enthusiast

jdubub

Posted
Posted

I noticed a decrease mostly in MPG when I threw on 285/65/18 from my stock 265/65/18, but they also weigh 20lbs. more per tire. I do know that I am going to find a lighter tire and go to a 275/65/18 either soon or just wait until there are bald.

Spurshot Senior Enthusiast

Spurshot

Posted
Posted

Just my 2 cents, but weight of tires and rims aside, taller tires will reduce the mechanical 'leverage' if you will, of the driveline. If you put identical tire/wheel weights on the truck but one set is taller, the taller tire will accelerate slower assuming neither tire is slipping/spinning. Lets say you are able to exactly match an axle gear set to give the same rpm vs speed with the tall and short tires. Even then, the taller tire will accelerate slower, assuming no slippage/spinning.

Stevens03 Senior Enthusiast

Stevens03

Posted
Posted

IF the new wheel and tire combo is a lot heavier (those Coopers are heavy) you can expect quite a difference in feel and even a drop in fuel economy. I know I lost about 1.5 mpg when I went to 20s on my truck... and I went with a pretty light tire and wheel combo. The Zeons are heavy tires.

 

 

x2 :thumbs:

Gurrzt Enthusiast

Gurrzt

Posted
Posted
Just my 2 cents, but weight of tires and rims aside, taller tires will reduce the mechanical 'leverage' if you will, of the driveline. If you put identical tire/wheel weights on the truck but one set is taller, the taller tire will accelerate slower assuming neither tire is slipping/spinning. Lets say you are able to exactly match an axle gear set to give the same rpm vs speed with the tall and short tires. Even then, the taller tire will accelerate slower, assuming no slippage/spinning.

 

That is because there is greater rotational mass on the taller set of tires.

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