Towing tire confusion

[BigBlue2024]

Hello. New to the community and I am hoping someone can clear up some confusion on tires. I recently purchased a 2024 chevrolet 2500 hd custom with 20" wheels w/ 275/65/17 tires. In the towing section it says my current setup is rated at 12k for a bumper pull trailer. (I have a 16k equipment trailer, long story) However, if I switch to stock 17 inch wheels w/ 245/75 17. I can get 14.5k. If I go stock 18 inch w/ 275/70/18 mt tires, I can get 16k. And if i had the zr2 package, I would have 305/70/18 mt tires (bigger than what i have now) and able to tow 16k.

heres my dilemma: I want to get more towing capacity when I need it in a second set of wheels and tires. I understand that more sidewall helps (smaller wheel) and a less overall diameter helps (smaller tire).

Here's the question: I have a set of stock 17 inch wheels from a 2018 silverado hd. I've found a 295/70/17 BFG tire with a similar load index (125 vs 126 that I have). It has more side wall than I have now (over an inch) and smaller diameter but not enough to throw the speedo way out. (About 1.5 mph at 60mph).

Would this combo get me at least to the 14.5k? Or is this wishful thinking. The wheels were new take offs in really nice shape so, I'd like to use them if I can. 

Thanks!

[mkirsch]

I'm surprised that in over two months, nobody pointed out that the OP was running 17" tires on 20" rims... Neat trick.

But yeah, if the ONLY difference is the tires and wheels, then putting better tires and wheels on the truck that are in line with the ones supplied by the manufacturer will give you the "rating."

In reality, the truck is already capable of towing the heavier weight, without changing the tires, as long as the tires are rated to handle the expected weight.

[Grit_dog]

Meh. OP is typical 1 n done. 
Goofy post. Lots of help. No response. 

[blt2ski]

😂 😆 😂

17" tires on 20" rims......

I believe the few of us reading this, realized the OP would get appropriate rims for tire size choosen. At least I did, or assumed by his typing he knew this.

Ultimately if you change tires, add overall weight, diam, you tow capacity goes down. Same diam or smaller with less weight, goes up!

I'm assuming load capacity per tire is greater than the load out on them.

Marty

[bid_time]

Theoretically, if the tires were the limiting factor when the manufacturer decided what the max towing limit of your truck is, then yes. However if the limiting factor is the transmission, drive shaft, frame, wheel hubs, axle shaft, brakes or any number of other such parts; then higher rated tires only mean that some other part(s) is going to break when you overload it.

[StirCrazy]

normaly the tires are the limiting factor, the other parts are enginered to have a fairly large saftey margin built into them, for example the rear end that is in my truck is actualy rated at twice the weight in a different brand of truck than it is in my ford, brakes are not usal anything to worry about when towing as anything that heavy has its own brakes.  automatic transmitions don't care about the actual weight but rather how you drive it to get their, they are rated for more power than the truck can put out.  now you might have to do services a bit more to keep the fluid looking nice and maybe install a cooler if it is tending to get warm onthe highway but thats it generaly.  standard transmitions on the other hand are a different story, haha.

to be honest I don't think you can get a tire rated high enough to worry about other parts within reason.  if you go to comercial 22" tires maybe but that isn't reasonable.  to me the higher rated tires are just to eliminate the only weak link that is around thoes capacities and reduce the chances of blowouts.  

[Grit_dog]

^Yup and even though the OP ditched the conversation, you have valid points, IF the truck in question was offered with different drivetrain components, ie different transmission or rear axle rating or gear ratios. 
However, that is not the case with new or newer GMs and hasn’t been for a while. 
I looked up the towing guide and it’s weird/laughable, and confusing when reading the towing rating sub notes as they pertain to tire sizes. 
afaik, the gassers (which the OP has although he didn’t say) only come with one final gear ratio and the definitely only come with one transmission. And the rest of the trucks are mechanically the same tip to tail. Only differences being weight of a longer model or 4x4 vs a reg cab 2wd. 
Yet the towing guide doesn’t necessarily follow that.   
just like the age old argument about 3/4 vs 1 ton ratings on here and other discussions, some ratings changes are purely regulation based ie gvwr ratings for purposes unrelated to the vehicles actual capacity compared to a similar model with all the  same underpinnings. 
This is the case here although at the extreme dumb end of understanding as related to tire size. 
Any of you look up the towing guide should conclude the same. 
Bottom line, for the OP, just tow what you want. If you’re within your tire weight capacity for rear axle weight and within the 33-34” diameters of the OE tire and rim options, you can ignore the stupid notes 3 and 4 that somehow assign extra towing capacity to mud terrains or 22” wheels options. They don’t compute. 

[StirCrazy]

---

@Grit_dog wrote:

just like the age old argument about 3/4 vs 1 ton ratings on here and other discussions, some ratings changes are purely regulation based ie gvwr ratings for purposes unrelated to the vehicles actual capacity compared to a similar model with all the  same underpinnings. 
This is the case here although at the extreme dumb end of understanding as related to tire size. 
Any of you look up the towing guide should conclude the same. 
Bottom line, for the OP, just tow what you want. If you’re within your tire weight capacity for rear axle weight and within the 33-34” diameters of the OE tire and rim options, you can ignore the stupid notes 3 and 4 that somehow assign extra towing capacity to mud terrains or 22” wheels options. They don’t compute. 

I have found a few differences between some gas and diesel as well as 3/4 ton and 1 ton trucks.  aside from a leaf spring here or there the biggest one I see is with the brakes, specificly the size of the rear ones.  I know for my truck I have to make sure they give me the big rear break pads and the proper rotars, aparently the gas 1 ton trucks use a smaller sized rotar which could be where some of the difference in towing capacity comes from.  also the 3/4 ton diesels have one less leaf than I do.  now this is ford also.. GM who knows what the subtle differences might be.  I also have the heavy payload package on mine, I am not sure what all that entails, maybe an overload, but part of it was a 20" rim and tires to match the increase in payload.

---

[blt2ski]

Bid_time,

If you look at the recent about 5-10 yrs ago, towing specs put out by ASE group, nowhere is it assumed that tire capacity per say is a limiting factor of one's tow rating. It;s generally speaking a performance factor. Acceleration, holding mph above 35 or 40 mph depending upon the total GCW of the vehicle in 100F temps on a 5% grade, NOT overheating mechanicals! Starting on in forward and reverse X times on a 12% grade and not overheating the mechanicals or brake fade. Ebrake holding gcw on an x% grade. Yes, you do need payload for the HW of the trailer plus # of occupant's times seatbelts at 150lbs per person. SOme cases, a 5W will be lower rated than a ball mount. a 10K trailer will need generally 10% or 1000 lbs to 15% 1500 lbs, vs a 5W at 2000-2500 lbs of HW for the 10K lb total weight trailer. If you only have 2000 lbs of payload, 3 seat belts, max trailer is around 10K in a ball or pintle hitch setup. A 5W is generally speaking out of the equation. 
Payload is the only real place tire capacity comes into play. As I noted, if tire capacity, axle, springs etc are too low for the payload needed, you have too small of the vehicle! doesn't matter if you are or are not towing.

At the end of the day, if you do not have the payload needed for the HW of the trailer, you have no trailer tow capacity!

Marty

[blt2ski]

BenK a past poster on here, possibly RIP as he was dealing with some BIG C issues. He helped design competition bicycles. He noted that the athletes would notice 1-2 ounces of less weight in a moving part, ie tire wheel combo, gears etc. vs it took 2 lbs to notice the reduction of weight in a non-moving part, ie the frame! So, a non-moving to moving part ration of 16-32 to one! 

Let's assume this ratio hold true in our trucks. If we reduce the tire and rim weight by 1 lbs, that is a saving of 16 to 32 lbs of weight equal in the bed. Two drive tires we have a total of 32-64 lbs saving equal. 4 tires on a dually, 64 to 128 lbs. 

Or as I did on my 05 DW DA combo, I kept the same tire size, a 215-85-16, went from a polyester sidewall tire, to a steel sidewall tire!  Toyo M55's to be exact. They were 10 lbs heavier than the typical steel tread, polyester sidewall tire. 40 lbs of tire, equals around 640 to 1280 lbs of non-moving weight! I lost around .5-1 mpg. To say at times I noticed this, I did, a lot of times no. Bryan who also used to post on here, noted the same difference in MPG when he did the same with his totally customized DW E350 ext van when he put Toyo M55's on his rig. He had a 6.8L V10 with a 4sp auto IIRC. 

BUT, mpg wise, I sure did. I did the same with my current 1500, went up an inch diam, but the tires are 10-12 lbs heavier being 10 ply 285-65-18 vs stock 265-64-18 XL tires. Ive lost 2-3 mpg depending upon driving conditions, and yes, my 285/305 4.3 V6 notices it a bit. BUT as also noted, I have a 6 sp auto, with 4.10 first gear, 3.42 rears, effective now a 3.23. I still out pull my BB 454's with TH 400 auto, 4.10 axle vs 2.48 first gear is tranny is taller than current setup. Along with three more gears to work with. 50 extra HP help, but down 80 lb ft of torque, but the gearing is an actual net torque multiplication, so easier to get the trailer at the same total weight going.  A bit easier with the stock 265 tires too. Next time around, I'm hoping I can find a 285 in an XL, or drop to a 275- 65-18. I can find these 2-3 lbs heavier than the stock tires. 

This is also one of the many reasons semi's are going with super singles. You can save 100-150 lbs total between the single 20" wide tire with aluminum rims, vs 4 10" tires on steel rims. Thats approx. 800-1200 lbs of unsprung weight gone! More payload, less HP needed to move the load!  For us driving 10-15000 miles a year, probably not worth it, but long haulers drive 80-120K miles a year, even local drivers can do 50-70000 miles a year. a .5 to 1 mpg increase, ie 8 to 9 mpg, pretty decent savings!

Choose your poison, I'll take the lighter tire setup frankly!

Also as far as GCWR goes, its a performance rating only! IF one chassis has a 12K lb rating, same chassis etc with a bigger motor, springs, tires, axle ratio, transmission is rated at 15K lbs. The 12K rated one will pull it safe and sanely, you will just be slower! OR, an equipment trailer vs RV TT, I got 1-2 mpg more, pulled 3-6% freeway grade faster and a gear taller at the same GCW! That was due to aerodynamics. Ea additional 3 sq ft of frontal area, is the same as adding/subtraction 1000 lbs to the vehicle total. I pulled upwards of 12K with my 96 6.5TD K3500, its rating was 12500, a BBV8 was highest at 20000 lbs. Other than HP, same torque with both, I'd go a bit slower with less hp.......

Many ways to look at how well your vehicle may tow!

Marty

[blt2ski]

Reality, put a smaller diam tire, your actual ratio will get lower numericly, making it easier to start a given load, you are running a few rpm more which equates to more HP at a give speed ....

From a manufactures warranty ratings standpoint, yes those tires can change the ratings. As a 2" smaller diam Ture will make a 3.73 effectively a 410. Like wise, a 2" diam larger tire will make a 4.10 effectively a 3.73.

Something you're not taking into account, tires with the same diam, say 31.5" iea 265-75-16 vs a 265-70-17 vs a 265-65-18. The 18" tires will be overall lighter assuming the same rim metal. As rubber tire part is heavier than aluminum. Steel rims it's the other way. The 18 will be slightly heavier. You need less HP to turn lighter rim tire combos, which gives you a higher trailer tow ability.

Also, a 65 series tire vs a 70, 75, series tire with leads sidewall, braking and acceleration are better due to less tire flex.

A 235-85-16 tire, vs a 265-75-16 tire. Same diam, same sidewall height, but one tire is an inch wider, has better handling than the narrower one. I had 235 snows, and 265 summer tires on two trucks. The 265 8 ply tires handled loads way better than the 235 10 ply tires. Both had 3000 lb capacities.

Reality, put whatever tire you want into on. A lighter overall combo, slightly wider has usually been better for me.

Tow ratings, are not enforceable from a cveo/Leo standpoint. Only axle ratings are used. You will NEVER hit the max to be consider over weight where you will have issues with an enforcement officer.

Marty

[valhalla360]

If you are drag racing, the weight of the tire and aluminum vs steel rims can make a difference as you have to accelerate that extra weight. Towing...technically it will make a difference but such a small one that it won't be detectable.

Larger diameter is likely the reason for the change in rating, though in the stock sizes mentioned by the OP, it's more like going from a 3.73 to a 3.95. Assuming the OP is towing mostly in flatlands, it won't be very noticeable other than with the 10speed transmission, it might pick a different gear and run at pretty close to the same RPM.  It's only in the edge cases where it might really make a difference. If you are loaded to the max, going up a steep grade and the transmission runs out of gears to drop down, it may eventually fail to get up the hill with the larger diameter tires but so long as it doesn't run out of gears, it will wind up running about the same speed & rpm.

This is different from the old days of 3 speed transmissions where huge change in gear ratio every time you dropped a gear and very quickly, you found yourself in 1st gear.  Also, the new 8/10speed transmissions, 1st gear is basically an extra deep granny gear, so you might be going slow but you will keep going.

What I don't understand is buying a truck with a 12/14.5k limit when you know you have a 16k trailer that you pull. 

[StirCrazy]

changing tires, won't increase your towing capacity. 

[slider45]

That's the straight answer.

[Grit_dog]

Assuming OP actually read this or comes back, confirming what you said. 
didn’t read the other long replies, but short of having some janky “custom” wheels, any 8 lug wheels will have enough load capacity to reasonably tow anything bumper pull up to 16klbs plus weight in the bed.