NorCal Wheeling, Camping, Recovery

[SlickRickMotoADV]

Larger tires increase your contact patch, which increases traction, and increased air volume in the tire also lets you air down to lower pressures, or to the same pressure with higher confidence of not breaking a bead.

That said, every change is incremental, and has potential cascading consequences - and driver skill ultimately is everything. If you don't want to change; you're certainly justified in remaining on 33s.

Did you allow for selling your current wheels/tires, or if they're nearing end-of-life, you'd soon be plunking down coin for new tires anyways?

Wheels vary wildly in cost, too. If you want to go to 17x8.5, there are some pretty affordable options out there - 100 to 125 per rim.

I just see no reason to get rid of what I have is all. I just recently bought the Rubicon wheels, nice spacers to gain clearance for the LCAs, etc. Tires are still in great condition. I have a friend lined up to buy the tires if I don't want them. I don't care much for the extra 1.8" tire width so much as the ground clearance factor. I thought it would be more than 0.8" though. I'd probably want a regear with 35 eventually too which just continues to add to the price. Looking at ~$4k all said and done, more if I get a locker or two. Ugh. It never ends!

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[bjm00se]

I don't care much for the extra 1.8" tire width so much as the ground clearance factor....

I did want to clarify one thing here: larger diameter tires have a larger friction contact patch even at the exact same tire width - and this effect is magnified when you air down.

Now, that being said, you wrote:

I just see no reason to get rid of what I have is all. .
...and...
Ugh. It never ends!

Totally. And forums like this do tend to feed the more, bigger, stronger, better treadmill.

So, you originally asked: is it "worth it?" well, the answer to that will vary from person to person. But it sounds like you're settling on your answer being - "No, it's not." Hey, man - I'll back you up and tell you you're doing the right thing.

Our Jeeps are really capable out of the box. I was driving some 4x4 roads this week that had my wife gripping the armrests and that didn't even begin to ruffle the Jeep's feathers, and this is completely box-stock. And you've already added a bit of a lift to help your breakover angle, which is arguably the biggest clearance problem in the JLUnlimited 4doors.

You're there. You've arrived. You've achieved your capability goals.

Stick with what you're running. Turn away from the "bigger, better, more" treadmill. Be happy.

 

[SlickRickMotoADV]

I did want to clarify one thing here: larger diameter tires have a larger friction contact patch even at the exact same tire width - and this effect is magnified when you air down.

Now, that being said, you wrote:


Totally. And forums like this do tend to feed the more, bigger, stronger, better treadmill.

So, you originally asked: is it "worth it?" well, the answer to that will vary from person to person. But it sounds like you're settling on your answer being - "No, it's not." Hey, man - I'll back you up and tell you you're doing the right thing.

Our Jeeps are really capable out of the box. I was driving some 4x4 roads this week that had my wife gripping the armrests and that didn't even begin to ruffle the Jeep's feathers, and this is completely box-stock. And you've already added a bit of a lift to help your breakover angle, which is arguably the biggest clearance problem in the JLUnlimited 4doors.

You're there. You've arrived. You've achieved your capability goals.

Stick with what you're running. Turn away from the "bigger, better, more" treadmill. Be happy.

Oh I hear you. Mostly just tired of dragging skids everywhere, but I honestly don't think 0.8" is going to help that. I have better stuff to spend $ on right now anyways, like an adjustable front track bar.

 

[zouch]

i see this a lot; let's check the math.

remember; PSI = Pounds per Square Inch,... why would 2 tires of different sizes carrying the same weight at the same pressure have different sized contact patches?
different *shaped* contact patch, yes. different total contact patch area; no.

what a taller tire will gain you is more clearance, greater air volume, and a larger radius which helps it roll over things more easily.
what it will lose you is smoothness through bumps at speed due to the (likely) increase in unsprung weight, and acceleration and braking efficiency due to that larger radius. acceleration efficiency can be regained through regearing.

I did want to clarify one thing here: larger diameter tires have a larger friction contact patch even at the exact same tire width - and this effect is magnified when you air down.

[snip]

 

[zouch]

if you have done any lift, you probably need at least an adjustable track bar for the front, and probably at least a track bar relocation bracket for the rear; possibly an adjustable track bar there, too. (i found that after adding a track bar relo brkt in the rear of mine my rear track bar was adjusted about back to the length of the stock bar.)
worry about tires later.

Oh I hear you. Mostly just tired of dragging skids everywhere, but I honestly don't think 0.8" is going to help that. I have better stuff to spend $ on right now anyways, like an adjustable front track bar.

 

[mikej]

I just see no reason to get rid of what I have is all. I just recently bought the Rubicon wheels, nice spacers to gain clearance for the LCAs, etc. Tires are still in great condition. I have a friend lined up to buy the tires if I don't want them. I don't care much for the extra 1.8" tire width so much as the ground clearance factor. I thought it would be more than 0.8" though. I'd probably want a regear with 35 eventually too which just continues to add to the price. Looking at ~$4k all said and done, more if I get a locker or two. Ugh. It never ends!

Something to think about: if you replace your tires down the road, odds are your friend won’t be willing to pay what he is now. And if you wait until they’re worn out, no one will pay you for them (you’re paying a disposal fee at that point). It’s worth considering making the move now while you have a buyer for something that is losing value and will eventually go to negative value.

 

[SlickRickMotoADV]

Something to think about: if you replace your tires down the road, odds are your friend won’t be willing to pay what he is now. And if you wait until they’re worn out, no one will pay you for them (you’re paying a disposal fee at that point). It’s worth considering making the move now while you have a buyer for something that is losing value and will eventually go to negative value.

I got the tires for free so no worries there.

 

[bjm00se]

i see this a lot; let's check the math.

remember; PSI = Pounds per Square Inch,... why would 2 tires of different sizes carrying the same weight at the same pressure have different sized contact patches?

Hmmm. It's a fair question. The answer is that air pressure in PSI within the tire does not exactly correspond to the ground loading of the vehicle on the ground, which is also measured in PSI.

IF the vehicle were to be sitting on perfectly flexible round balloons instead of tires, this would be so. But tires have very rigid and shaped casings.

This guy uses real tire manufacturer data to show that ground loading does not correspond to internal pressure in nearly the way you would expect:

https://www.enginebasics.com/Chassis Tuning/Tire Contact Patch.html

(He's doing sportscar autocross stuff, not offroading, but the basic point that ground loading doesn't necessarily cross over to internal pressure is the main point.)

 

[zouch]

sorry guess i wasn’t clear enough.

we’re talking here about comparing contact patch areas of different sized tires at the same pressure, not comparing different pressures in the same tire.

Hmmm. It's a fair question. The answer is that air pressure in PSI within the tire does not exactly correspond to the ground loading of the vehicle on the ground, which is also measured in PSI.

IF the vehicle were to be sitting on perfectly flexible round balloons instead of tires, this would be so. But tires have very rigid and shaped casings.

This guy uses real tire manufacturer data to show that ground loading does not correspond to internal pressure in nearly the way you would expect:

https://www.enginebasics.com/Chassis Tuning/Tire Contact Patch.html

(He's doing sportscar autocross stuff, not offroading, but the basic point that ground loading doesn't necessarily cross over to internal pressure is the main point.)

 

[bjm00se]

sorry guess i wasn’t clear enough.

we’re talking here about comparing contact patch areas of different sized tires at the same pressure, not comparing different pressures in the same tire.

Yes we were. I agree. The point is - contact patch is a specific area, and is measured in PSI - the pressure of the vehicle on the ground.

But you can't back-calculate the size of that patch based on the PSI in the tire. Because the PSI on the ground isn't necessarily the same as the PSI in the tire. And the reason this is so is the size, shape, and rigidity of the tire casing, unlike a perfectly flexible balloon.

So once they don't match up exactly, it's no longer possible to assert that different sized tires will have the same size contact patch based solely on the internal tire air pressure.

I haven't proved that the MUST be different. I've only cited a source that it's not possible to reliably claim they're the same.

Good discussion, but I'm off to other stuff now. You can drop the last word on this topic. :-D

 

[zouch]

OK, you had said:
“larger diameter tires have a larger friction contact patch”, but now it sounds like you’re saying that’s not necessarily true.

so maybe we now agree after all!

Yes we were. I agree. The point is - contact patch is a specific area, and is measured in PSI - the pressure of the vehicle on the ground.

But you can't back-calculate the size of that patch based on the PSI in the tire. Because the PSI on the ground isn't necessarily the same as the PSI in the tire. And the reason this is so is the size, shape, and rigidity of the tire casing, unlike a perfectly flexible balloon.

So once they don't match up exactly, it's no longer possible to assert that different sized tires will have the same size contact patch based solely on the internal tire air pressure.

I haven't proved that the MUST be different. I've only cited a source that it's not possible to reliably claim they're the same.

Good discussion, but I'm off to other stuff now. You can drop the last word on this topic. :-D

 

[SlickRickMotoADV]

Headed to Slickrock tomorrow as a passenger in my friend's heavily modded JLU and JT. Can't wait to see what the guys on 38"+ and aftermarket everything can do. I might poop myself.

 

[Sunshne×Whsky]

Need opinions from yall.

I'm currently on 33s (32.8" in reality) with a 2" lift. Was considering moving to 35s (34.4" in reality). I'm looking at almost $2500 to support that though, and only getting 0.8" more ground clearance. I'm not sure if that's worth it. Can't go any larger than 35 without axle work or replacement on these base model micro axles. I'm starting to feel like $2.5k for 0.8" isn't worth it. What do you think?

I haven't been "unable" to do any of the trails that I want to, but I'm the only guy in the group regularly laying skids to the ground. I guess that's the point of them though.

Do it. An inch is an inch. The extra inch will help, but you’re still gonna be dragging skids. But that’s why they are there. We went 35s from the 33s and it helped clearance and confidence. As far as the price, that’s your call. Everyone sees value differently.
How was Slickrock? Heard it’s gettin good.

 

[SlickRickMotoADV]

Do it. An inch is an inch. The extra inch will help, but you’re still gonna be dragging skids. But that’s why they are there. We went 35s from the 33s and it helped clearance and confidence. As far as the price, that’s your call. Everyone sees value differently.
How was Slickrock? Heard it’s gettin good.

I didn't take my own vehicle to slick rock (don't think it would have made it), but it was a blast in my friend's rock crawling JLU and JT. Lots and lots of skid dragging, one or two winching points, lots of lockers, etc. It was pretty freakin crazy. Fun to be a passenger for most definitely.

I'm leaning towards keeping these 33s until I run them out and see if I end up on anything that makes me think I need to go bigger in between now and then. There was only 1 trail I've been on that made me want that, and I don't really see myself going on that kind of stuff again any time soon.

 

[SlickRickMotoADV]

Going to South Cow Mountain this weekend with some friends. Anyone want to join?

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