Jump to content

Recommended Posts

Posted
On 5/10/2025 at 3:32 PM, GETGONE said:

 

I've run mine to 112 countless times with zero issues. 31K miles and still going strong. Took it to a test and tune and ran about a dozen passes trying various launches, no issues. Best of 14.2 in the 1/4.

 

Nice time!  If memory serves, that 112 mph problem applied to K2 1500s.  I recently learned that my kids have been exceeding 112 with their GMT900s with 6.2s too!  

Posted (edited)

Driveshaft seems to get a lot of the press, but tire speed rating should be looked at too. 

(yes, I realize that exceeding speed rating isn't likely to cause immediate failure...)

 

Do they know about tire speed ratings? 

 

Speed (and load) rating will also be on the tire.

Factory tires on my '21 were speed rating S.

 

image.png.5304200992d5297646c02b5c85367739.png 

 

 

S

An S speed rating indicates the tire has been approved for speeds up to 112 mph (180 km/h) under optimal conditions. Everyday passenger vehicle tires can be S speed rated, but S tires often prioritize specific performance or function. Many all-terrain LT tires are becoming available in an S rating as that’s the OE spec for many of these vehicles like the Ford Raptor. 

 

 

This is was on a set of Duratracs I used to have.

Load load rating 109, speed rating S

image.png.a570718ea773e27958721328faf017bd.png

 

 

Current '23 has  275/60R20 115S 

So again, speed rating S 

 

My current winter tires are speed rating R.

 

Speed rating R allows for speeds up to 106 mph (170 km/h) under optimal conditions. Like Q, R tires generally prioritize a particular function or unique performance over maximum speed capability. R speed tires are rare but can be found on some heavy-duty light truck (LT) tires, as well as studdable and studless winter tires.

 

Edited by redwngr
Posted

 

Speed Rating Miles/Hour KM/Hour Typical Application(s)
L 75 120 Trailer tires
M 81 130 Spare tires
N 87 140 Spare tires
P 93 150  
Q 99 160 Select winter tires
R 106 170 Passenger and light truck tires
S 112 180 Passenger and light truck tires
T 118 190 Passenger and light truck tires
U 124 200  
H 130 210 Passenger sedans, coupes, SUV and CUV’s tires
V 149 240 Performance sedans, coupes, and sports cars tires
W 168 270 Performance sedans, coupes, SUV and CUV’s tires
Y 186 300 Exotic sports cars tires
Z 149+ 240+ High-Performance vehicle tires
  • Like 1
Posted

Trail Bosses with the 18" tires are electronically limited to 98mph due to tire rating. The 20" wheel option bumps the limiter up to 112mph because of the S speed rated tires.

Posted
3 hours ago, swathdiver said:

 

Nice time!  If memory serves, that 112 mph problem applied to K2 1500s.  I recently learned that my kids have been exceeding 112 with their GMT900s with 6.2s too!  

LOL. Busted.

 

My 2000, GMT800, that I still have, has a 128 limit. I have seen 4000 rpm`s in overdrive with 16 inch wheels and 3.73 gears. Poor 100 mph speedo.

  • Like 1
Posted (edited)
16 hours ago, PunchT37 said:

LOL. Busted.

 

My 2000, GMT800, that I still have, has a 128 limit. I have seen 4000 rpm`s in overdrive with 16 inch wheels and 3.73 gears. Poor 100 mph speedo.

I'm curious what the tire loading label on the doorpost lists as the speed rating?

Edited by redwngr
Posted
1 hour ago, redwngr said:

I'm curious what the tire loading label on the doorpost lists as the speed rating?

S. But, this truck has a whole new computer.😉

Posted
4 hours ago, PunchT37 said:

S. But, this truck has a whole new computer.😉

 

Thanks.

 

So if they were installing S rated tires on (at least some) 2020's the original limiter was likely lower/

 

 

 

 

Posted
4 hours ago, redwngr said:

 

Thanks.

 

So if they were installing S rated tires on (at least some) 2020's the original limiter was likely lower/

 

 

 

 

 

4 hours ago, redwngr said:

 

Thanks.

 

So if they were installing S rated tires on (at least some) 2020's the original limiter was likely lower/

 

 

 

 

Factory limiter on that 2000 truck was 96 mph.

  • Thanks 1
  • 5 months later...
Posted (edited)

I have yet to top mine out since I had it unlocked and then tuned it (High Country 6.2 10 spd), but my tires will limit me as I have a brain. But damn the ecm and tcm tune feels great. If anybody is on the fence, just do it. I'm still tweaking some of the shift times to get rid of the sluggish shifts on lower power shifts. mid power shifts are .200 seconds and full power are .100 seconds, tires chirp with only a small boost in pressure and reducing shift times.

Edited by Silveradgo
Posted
10 hours ago, Silveradgo said:

I have yet to top mine out since I had it unlocked and then tuned it (High Country 6.2 10 spd), but my tires will limit me as I have a brain. But damn the ecm and tcm tune feels great. If anybody is on the fence, just do it. I'm still tweaking some of the shift times to get rid of the sluggish shifts on lower power shifts. mid power shifts are .200 seconds and full power are .100 seconds, tires chirp with only a small boost in pressure and reducing shift times.

Who tuned it and how much did it cost you?

Any mods beside the tune?

Posted (edited)

I tuned it. Only have a K&N Blackhawk intake on it for the sound. Longtubes will be the next go-fast mod.

 

Edit: I'll have to get a video of the induction noise during the 1-2 shift at like 4.5k 🤤

Edited by Silveradgo
Posted

How did you tune it since you have to send in the ECM last I knew to get it unlocked to be able to tune it.

Posted
8 hours ago, GETGONE said:

How did you tune it since you have to send in the ECM last I knew to get it unlocked to be able to tune it.

See my earlier post

Posted
4 hours ago, Silveradgo said:

See my earlier post

You have 3 posts. You just said you had it unlocked and you tuned it. That tells me NOTHING. WHO unlocked it? WHAT are you using to tune it? New member sounds like a troll.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Latest Articles

  • Posts

    • You must have that upgraded gvw package which is only available or at least was in 2025 with the diesel engine for the 3/4 ton and that gave the truck physically the larger 12.0 ring gear rear diff and the 3500 rear spring pack. There is a difference in what the diff housing looks like externally as one tell tale and also your truck should have the upper overload spring pack and the frame pads that the pack goes up against.    The pressure the tpms system kicks the alarm in on a stock setting truck, that is a good question and was just from what I recall but I doubt I made any notes on it as I knew for the rear that it was not at all what I was after regardless either. Being that you have a diesel and if running on stock tires the minimum pressure on an empty truck seems to be around 50 psi from hearing of those that have weighted the front axle but the rear axle is very similar in weight to a gas truck and again a near empty truck on the rear could go down to 35 pounds at minimum. However the weigh scale is the proper way to know for sure as a guide.    As to changing the readings on the dash from metric to the US measuring system, oh yes that is done easily but what I was attempting to explain was that I can't pick and choose items I want to have in US and those I still want in the metric system at the same time as its either all or none. For example lets say you drove into Canada and switched your dash over to metric so your speedometer read in km an hour, well then your reading kilopascals on your tpms readout and your wife looks over and says what the hell is that saying in the tpms screen and you say "darned if I know, I think its Chinese" !
    • This is partly why I decided to have switched over to Amsoil SS as a way of hopefully preventing the buildup of the sludge/carbon on the pistons and clogging of the oil control rings and the carbon that would cause the compression rings to stick in their grooves as well as stay cleaner up top of the heads in the valve train in the first place, an oil that has tested better by third party testing over typical shelf oil and also doing my best to run relatively short OCI. However in saying that I don't think there is any way to easily prove the oil I was using prior allowed for a buildup at the OCI I was doing, nor in the other direction to make claims the Amsoil is keeping everything clean either. There really isn't a window into the engine is there to know anything for certain even if oil samples were taken for example that showed still healthy oil being dropped out of the oil pan other than engine tear downs that extensive and expensive testing of oils does to actually visually see what is really going on inside the engine. I wish there was some easy method of seeing what is going on but I don't happen to be aware of that if there is.  
    • My truck is a ¾ ton but my placard also says 80 for the rear tires, I think I might have the upgraded suspension to the 3500 series maybe.   I put my air down to 60 and the light was still on, and there was no way I was putting over 60 psi in the rear empty and not towing because I knew the actual number Toyo gave me and I didn't wanna ruin the center of my tires!   And you actually can change it in the settings from metric or is and it will show kph or mph then when you go into your tire settings it will be either psi or kpa, but it would be nice to just change it directly on the tire psi page 
    • Common Sense Assembly   Your driveline is forgiving of the occasional mistake. It will even often forgive the random serious blunder. But it will not forgive a continuous bad habit.      What? Not everything needs to be a five thousand word essay.       
    • We drove about 15 minute east today to visit a friend and saw a steep increase in price in the same county. About 50 cents a gallon steepper. 
  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...