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Largest stock tire
Posted: Fri Aug 21, 2015 9:34 pm
by redneck1
Hey guys fixin to get some new cooper stt pro mud tires and wondering what's the largest size we can put on a stock 4th gen?? Hopin to get 315/70/17 wich is 34.5s thanks
Re: Largest stock tire
Posted: Fri Aug 21, 2015 9:48 pm
by RotorWolf
Shouldn't be a problem at all, stick with the factory rims/offset and you'll be fine.
Re: Largest stock tire
Posted: Fri Aug 21, 2015 10:40 pm
by redneck1
Thanks
Re: Largest stock tire
Posted: Fri Aug 21, 2015 11:51 pm
by Jack187
redneck1 wrote:Hey guys fixin to get some new cooper stt pro mud tires and wondering what's the largest size we can put on a stock 4th gen?? Hopin to get 315/70/17 wich is 34.5s thanks
I'm running 37" pros right now on my 2015 with no lift. Pretty sure you will be fine with the 315s on any of the 4Gs, regardless of the suspension.
Re: Largest stock tire
Posted: Sat Aug 22, 2015 8:34 am
by JBM Power Wagon
You will be good. Depending on the "true" tire size you may have some rubbing at full lock on the radius arms and bolts. If you do you just have to be careful to not do a lot of full lock turns which can cause the radius arm bolt to groove the tires. I've been running 315/70/17 tires on my '14 for a year and love it.
Re: Largest stock tire
Posted: Sat Aug 22, 2015 11:16 am
by RotorWolf
Did you re-calibrate the speedo after installing the 37's??
The only thing holding me back from installing 37's, is I can't find a tuner...
Re: Largest stock tire
Posted: Sat Aug 22, 2015 8:44 pm
by Snowsled
Jack187 wrote:redneck1 wrote:Hey guys fixin to get some new cooper stt pro mud tires and wondering what's the largest size we can put on a stock 4th gen?? Hopin to get 315/70/17 wich is 34.5s thanks
I'm running 37" pros right now on my 2015 with no lift. Pretty sure you will be fine with the 315s on any of the 4Gs, regardless of the suspension.
I am really itching to do 37s... Do you have some pics you could share? Have you tired it off road? They need to work when stuffed into the fender wells for me

Re: Largest stock tire
Posted: Sat Aug 22, 2015 9:32 pm
by stubiePW
I'm running 37s as well with some rub. Nothing bad. I also have a Diablo tuner
Re: Largest stock tire
Posted: Sat Aug 22, 2015 10:53 pm
by 2011TXPowerWagon
I am also running 37's with stock wheels and stock arms. Minor rubbing but it's not a deal breaker.
Re: Largest stock tire
Posted: Sat Aug 22, 2015 11:37 pm
by RotorWolf
So, any speedo recal???
Re: Largest stock tire
Posted: Sun Aug 23, 2015 3:07 am
by 2011TXPowerWagon
Nope I didn't. According to my GPS I'm about 5mph off
Re: Largest stock tire
Posted: Sun Aug 23, 2015 6:45 am
by Will
I'm on 37's and a Diablo. Better mpg than stock.
Re: Largest stock tire
Posted: Sun Aug 23, 2015 9:42 am
by loveracing1988
RotorWolf wrote:Did you re-calibrate the speedo after installing the 37's??
The only thing holding me back from installing 37's, is I can't find a tuner...
Don't hold your breath from diablosport either. I have a 2014 and my intune fails every time it tries to reprogram the tire size. I just updated it yesterday and it now fails to tune my truck as well.
Re: Largest stock tire
Posted: Sun Aug 23, 2015 12:37 pm
by Will
I don't get how some have problems with Diablo and others don't. I've changed my tune more times than I can count and the only hiccup I had was when I opened the door while it was loading. Turn everything off and don't touch anything is what I do.
Re: Largest stock tire
Posted: Sun Aug 23, 2015 8:00 pm
by loveracing1988
Will wrote:I don't get how some have problems with Diablo and others don't. I've changed my tune more times than I can count and the only hiccup I had was when I opened the door while it was loading. Turn everything off and don't touch anything is what I do.
If yours is a 2010 that explains it, it seems like for 2014 they changed everything so no matter what it is a pain to do computer wise, and for 2015 it got even worse.
Re: Largest stock tire
Posted: Sun Aug 23, 2015 10:21 pm
by Jack187
I sent emails to Diablosport and Hypertech. Diablo said they were working on one, but no ETA. Hypertech sent an email saying the speedo calibration unit for a 5.7L 2015 2500 would work, but someone else on this board called Hypertech and was told it would not work. I've just gotten used to adding 10% to the speedometer for the 37s. It becomes automatic after a while.
Re: Largest stock tire
Posted: Sun Aug 23, 2015 11:47 pm
by Stickman
It was the same story with Diablo when I bought the Trinity for my '12 back in '13. It took them a little over year to get it to where everything worked well with no glitches or hiccups. I updated it 3 times over the first 6 months after I bought it and every time some little thing would either not work or would cause it to freeze and crash. And I bought it later than everyone else, so I bet it took 1 1/2 or close to 2 years from release for them to straighten it all out.
Re: Largest stock tire
Posted: Mon Aug 24, 2015 6:46 am
by Will
loveracing1988 wrote:Will wrote:I don't get how some have problems with Diablo and others don't. I've changed my tune more times than I can count and the only hiccup I had was when I opened the door while it was loading. Turn everything off and don't touch anything is what I do.
If yours is a 2010 that explains it, it seems like for 2014 they changed everything so no matter what it is a pain to do computer wise, and for 2015 it got even worse.
Yes, mines a 2010, but it's the same thing every year including back in 2010...hope they get the new ones figured out for yall soon because it sure is nice.

Re: Largest stock tire
Posted: Mon Aug 24, 2015 9:08 am
by JBM Power Wagon
Jack187 wrote:I sent emails to Diablosport and Hypertech. Diablo said they were working on one, but no ETA. Hypertech sent an email saying the speedo calibration unit for a 5.7L 2015 2500 would work, but someone else on this board called Hypertech and was told it would not work. I've just gotten used to adding 10% to the speedometer for the 37s. It becomes automatic after a while.
When I bought my 2014 and went straight to 315/70/17 tires the dealership bought the Hypertech speedo recal unit and it worked for mine.
Re: Largest stock tire
Posted: Tue Aug 25, 2015 10:20 am
by Jack187
It is funny how the world sometimes aligns itself to your thoughts. I was driving in to work this morning and thinking to myself "do I really need 37" tires?" I don't do a lot of off road any more, although in the winter I do hit a lot of snow. About that time, another truck pulls up along side me at a stop light. It was sitting a few inches higher than my stock height PW. It was a blacked out GMC with probably 9 inches of lift, sitting on what appeared to by 33" tires. I just laughed a little bit inside and once again felt pretty good about choosing my Power Wagon and my 37s. Thanks for the positive reinforcement, world!
Re: Largest stock tire
Posted: Tue Aug 25, 2015 4:04 pm
by Turkeytrak
redneck1 wrote:Hey guys fixin to get some new cooper stt pro mud tires and wondering what's the largest size we can put on a stock 4th gen?? Hopin to get 315/70/17 wich is 34.5s thanks
I put a new set of CooperSST on my 2014 PW a month ago, thet are LT351/70R17.The spec says they are 35 and 3/4, no problem clearing.
Re: Largest stock tire
Posted: Tue Aug 25, 2015 4:13 pm
by 04Ram2500Hemi
I've always felt the "largest size tire on stock setup" is kind of a loaded question. A lot of it depends on what suspension you have on your Power Wagon (old or new), and are you ok with rubbing on the control arms? On the old suspension if you go with a 12.50" wide tire you're going to rub on the control arms, but I don't know about the new suspension. I didn't want to mess with any kind of lift or rubbing, so I replaced my stock tires with 285/75/17 Toyo A/T II Tires knowing that they were a little bigger than stock, and I also knew I wouldn't rub on the control arms. Maybe down the road I'll go a little more extreme and throw some Thuren Control Arms and 37" tires under my truck, but for now I'm happy with my setup. That, and I really hope these tires last a long time, they were expensive!
Re: Largest stock tire
Posted: Thu Aug 27, 2015 5:50 pm
by GunniPWguy
There's a Cooper STT Pro ? I'm running a year old set of 35 x 12.5 STT's. Wasn't aware of a professional model
Re: Largest stock tire
Posted: Thu Aug 27, 2015 9:08 pm
by Jack187
GunniPWguy wrote:There's a Cooper STT Pro ? I'm running a year old set of 35 x 12.5 STT's. Wasn't aware of a professional model
They released about 3 months ago. They are replacing the STT from what I have read.
Re: Largest stock tire
Posted: Thu Aug 27, 2015 9:16 pm
by SheepdogOutdoorsman
My 37's rub a little on the upper control arms, but the worst part is how much they rub on the sway bar ... Damn near shudders the truck apart ... I'm looking into some options to fix the issue
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