Always fun times when the question is definitively answered by the 3rd post in the thread........then we all spend a week debating anyways, lol.
Are we talking payload or towing?Just as lowering a Rubicon, putting max tow springs and tires, etc in it won't change the rated capacity, lifting won't change it either. Added weight will lower payload as you are already closer to the gross weight rating but the number doesn't change. Some will argue that the higher center of gravity and larger tires will lower your capacity, but the rating is the rating period. Obviously it won't stop as well or handle as well as it did stock, but that doesn't change the numbers. That's like arguing our speed limits should be decreased after lifting or putting bigger tires on. The enforceable number doesn't change and has plenty of safety margin built into it in my opinion. My mojave is only rated at 6k pounds...before the 3.5" lift and 37s. And yet it had no problem towing an 8400 pounds trailer 600 miles including a grade that goes from 300' elevation to 4k feet in 20 miles. Maintained 65mph, stopped without issue, no sway, and never got above normal operating temps. Allegedly.
I think anyone who's ever towed, or at least the ones who've towed heavy knows that the ratings are conservative. Again changing springs whether they are HD stock height or lift springs won't change the rating tow period. They won't change the rated payload either. Now granted if you go with a light weight spring you'll get more sag vs one with a higher rating but that doesn't change your payload rating. Going to 1 ton axles with no other changes will obviously improve towing ability as they are far stronger, generally have bigger brakes, and the added weight being unsprung they will make the tow rig more stable without adding any load on the springs... and yet the rating not only doesn't change you effectively lose payload and towing capacity as you are now closer to the GVWR and GCWR numbers even when empty. Would it be safer to tow a 7,700 pound trailer with a JT on 1 ton axles vs a stock max tow everything else being equal? Obviously. Would you actually be over your GCWR? Most likely. And since payload is calculated by subtracting the vehicle weight, occupants, etc from the GVWR you'll lose payload even though logically it should have at a minimum stayed the same if not went up. Of course if you aren't a commercial vehicle you'll likely never be put on a scale, questioned about payload, etc.
I couldn't agree with you more. With all the "intelligence" available here, towing is more than just putting a pile of parts together. It's how they all work together. Pick a number, I'll say 50, and you change one of them and you can affect the towing. It's much more than the obvious horsepower of the motor or strength of the transmission, etc.
Some guys live to post "it's already been answered", "use the search", etc like the forum is closed and we should just read old threads. If you don't want to answer the same questions or engage in the topic....don't?
Search does not always help either lol.
Jeep.com is the last place for reliable info. It shows the tow rating of the rubicon as 4500 pounds not the 6k it really is for instance. That's like asking the service advisor at the dealer mechanical questions.
Your welcome.
Bill you covered the tires size and ECT before I.
Don't forget the "when properly equipped". That 4500 is totally accurate - unless you spring for the automatic transmission. So technically a Rubicon is only 4500 pounds.
You have to dig deep into the engineering side of things, and even where they talk about non-Jeep vehicles and engines in general, loading, towing and so on - and it talks of the sweet spot for heat vs. load vs. RPM.Your welcome.
Bill you covered the tires size and ECT before I.
Along with what I was going to add too.
I can really show the difference between Max-Tow and tire change size difference with over 30000 miles towing with stock 245/70r17 tires and 33/10.5r17 tires. It's a big deal and difference! The heat rejection is real along with mpgs. That I've seen towing a light trailer of 1500 lbs and of over 3000 lbs to include many trips to same places. Third set of tires, first 245's AT (stock), 245's HT (stock) and 33/10.5r17. the latter both were a MPG hit the current on towing too.
FYI: To give idea of miles towing on second set of tires on a few trailers. Two boats, travel trailer, two utility trailers.
Sidenote #2: Squirrelly (wandering) handling I noticed on lower than 50 psi in first two in general.
True, but typically the when properly equipped asterisk is listed next to the top payload and towing capacity not the minimum. They're all properly equipped for 4500. With the JT heat is probably the #1 concern in towing capacity, but that's not been the case in most full size trucks. Even in the JT is over hyped, as it passes the long grade in 90⁰+ temps to get that rating. No a base sport isn't going to overheat pulling a 6-7k pound boat home from the marina in 70⁰ weather with no elevation gain even with its 3.73s.Don't forget the "when properly equipped". That 4500 is totally accurate - unless you spring for the automatic transmission. So technically a Rubicon is only 4500 pounds.
This is from Jeep.com ->
You have to dig deep into the engineering side of things, and even where they talk about non-Jeep vehicles and engines in general, loading, towing and so on - and it talks of the sweet spot for heat vs. load vs. RPM.
There's a 4x4 truck site that goes into the details of why and how modifications take away, not add to, payload and towing. And the place putting it on sells lifts and after-market truck equipment.
Another guy from Australia, I believe, goes into the details of modern vehicles controlling trailers using the ABS system, calculating angles and so on, and applying one brake at a time in just the right place at the right time to mitigate sway and they talk of how changes to the vehicle mess with that.
Like so many things, it's not easily covered in a forum post.
