Nose up...Nose Down...What???

[Jtraskell]

I'm having a hard time seeing how a noticeable change in straight on nose dive would occur with no other change except switching from a P type to an LT tire (same dimension, same psi). Stiffer sidewall is going to be offset to some degree by slightly smaller air chamber volume as well as the fact that air pressure utterly dominates sidewall construction as a stiffening agent, especially for straight compression. There should be very little difference in deflection per load/psi between the two tires.

On the other hand, I can imagine a difference being felt, at least under hard braking, where the mechanism is different. Namely, the LT tire takes longer to slow the truck due to both more weight and less traction, resulting in less nose dive.

JB, IMHO the best one can hope for with nose dive improvement with stiffer side walled tires from the OEM, is possibly a couple of inches. The rest is suspension, springs, shocks etc. But even those couple of inches makes the nose dive action more manageable and less noticeable. Again, IMHO. The best way I can explain it is by analogy. Take a new roll of paper towels. Lay it on your kitchen counter, then press down on it toward one end. It squishes. So does your P rated tires when the brakes are applied firmly and at a fair speed. Now try to do the same with a roil of say visqueen. Pretty hard to squish. Still can be done, but one must use a lot more force. That to me is the difference between the P rated and in my case, D load LT tires.

Be safe.

 

[Boaz]

Great discussion fellas. I think the quick answer is to upgrade the shocks to bilstein 5100's, and I am probably going to do that. Even if I had the front set at .85 up from factory, I suppose I would have to align the front end after that??

I was googling around yesterday for prices on 5100's.... I see the application for 2011 but none for 2012.... I would imagine they are the same... ???? Might have to wait a bit for bilstien to come out with the "2012" set....

 

[Stifler]

Great discussion fellas. I think the quick answer is to upgrade the shocks to bilstein 5100's, and I am probably going to do that. Even if I had the front set at .85 up from factory, I suppose I would have to align the front end after that??

I was googling around yesterday for prices on 5100's.... I see the application for 2011 but none for 2012.... I would imagine they are the same... ???? Might have to wait a bit for bilstien to come out with the "2012" set....

same same. Shockwharehouse.com has great prices on them... I ran 5100s on my tundra and they do stiffen the right a bit but I still think the coils are the culprit here.

 

[mtbnole]

how much do the 5100's firm up the rear? my concern with just switching to 5100's and leveling the front is that with any significant amount of weight in the cargo area and you've got "reverse rake"...

????

 

[Jtraskell]

how much do mthe 5100's firm up the rear? my concern with just switching to 5100's and leveling the front is that with any significant amount of weight in the cargo area and you've got "reverse rake"...

Can't give you first hand since I do not own them, but if you do a search you will find many threads re-5100's. As I remember, that question has been addressed and answered more then once and I THINK it was said, no problems. They are stiffer shocks and the ones designed for the rear are NOT adjustable. Also, I think they also said that they raise the height of the rear a little. You should not have any sag in the rear unless you place a lot of load back there.

Be safe.

 

[1engineer]

I'm having a hard time seeing how a noticeable change in straight on nose dive would occur with no other change except switching from a P type to an LT tire (same dimension, same psi). Stiffer sidewall is going to be offset to some degree by slightly smaller air chamber volume as well as the fact that air pressure utterly dominates sidewall construction as a stiffening agent, especially for straight compression. There should be very little difference in deflection per load/psi between the two tires.

On the other hand, I can imagine a difference being felt, at least under hard braking, where the mechanism is different. Namely, the LT tire takes longer to slow the truck due to both more weight and less traction, resulting in less nose dive.

OK so for S&Gs I went out and aired up from 32 to 40 psi and there is no difference at all except I feel the road more as I am driving... still nose dives as it did with 32... although this may have "some" play in to the nose dive it isnt enough to warrant the cost of new tires.... unless of course you want cooler tires lol I understand the rigidity of the sidewall and compression at stop but I think in the case of the 4R it is 98% suspension related. I would even go further to say shock wouldnt be enough to improve it much I higher spring rate in the coil is most likely the NEED

Unfortunately we are all using the only tool we have at our disposal to determine the effectiveness of tires or suspension - the seat of our pants - and that is as different as we are.

The new tires I put on helped quite a bit in handling and a little with nosedive. That is my opinion and I am pleased with the performance. Philsey has not noticed much of a change. Several others have noticed varying degrees of improvement with either just tires, shocks, springs or a combination of all three. Again, those are their opinion. The OP asked our opinion because really there is no way short of developing some type of instrumentation involving pressure transducers to measure actual nosedive under hard braking. Even if we did somebody would say theirs was different though lol.

 

[Stifler]

5100s do not raise the rear at all. They do however accommodate for more lift.

 

[Stifler]

Unfortunately we are all using the only tool we have at our disposal to determine the effectiveness of tires or suspension - the seat of our pants - and that is as different as we are.

The new tires I put on helped quite a bit in handling and a little with nosedive. That is my opinion and I am pleased with the performance. Philsey has not noticed much of a change. Several others have noticed varying degrees of improvement with either just tires, shocks, springs or a combination of all three. Again, those are their opinion. The OP asked our opinion because really there is no way short of developing some type of instrumentation involving pressure transducers to measure actual nosedive under hard braking. Even if we did somebody would say theirs was different though lol.

Oh I am not discounting that tires make a difference... just that changing tires is NOT going to eliminate nose dive more effectively than shocks and coils. Going from a P to E rated tire obviously would "stiffen" the sidewall compression.... but again that isnt going to alleviate nose dive

 

[philsey]

Well, I'm headed up to my marina soon, which is a 45 min drive across town and highway. I'm airing up to 1-E's 37# first ... so, we'll see what happens.

 

[1engineer]

Well, I'm headed up to my marina soon, which is a 45 min drive across town and highway. I'm airing up to 1-E's 37# first ... so, we'll see what happens.

Good luck! What tires did you get again?

 

[philsey]

Good luck! What tires did you get again?

"Continental CrossContact™ LX20

The Premium SUV, Crossover & Light Truck All-Season Tire"

 

[4ShoreRunner]

5100s do not raise the rear at all. They do however accommodate for more lift.

Yeah, my rear 5100s did nothing to raise the rear OR stiffen up the rear.

 

[Jtraskell]

5100s do not raise the rear at all. They do however accommodate for more lift.

Yea, after posting, another neuron kicked in about an hour later ( they are getting fewer and kicking in later as time goes on....) and I think the post that I was referring to was one where the poster installed the rear 5100's AND spacers. Thanks for the correction. Be Safe.

 

[Jtraskell]

Yeah, my rear 5100s did nothing to raise the rear OR stiffen up the rear.

I thought the 5100 were stiffer. Didn't some of the members here install them to help with towing? (less sag). I know, many used the airlift products, but I thought Bilstiens were also an option.....ok, neurons are already in doubt. I should just have another beer and ponder.......

 

[Stifler]

shocks do nothing to help with load carry..... they may help the "feel" by dampening more/better but weight is weight.

 

[JB.]

JB, IMHO the best one can hope for with nose dive improvement with stiffer side walled tires from the OEM, is possibly a couple of inches. The rest is suspension, springs, shocks etc. But even those couple of inches makes the nose dive action more manageable and less noticeable. Again, IMHO. The best way I can explain it is by analogy. Take a new roll of paper towels. Lay it on your kitchen counter, then press down on it toward one end. It squishes. So does your P rated tires when the brakes are applied firmly and at a fair speed. Now try to do the same with a roil of say visqueen. Pretty hard to squish. Still can be done, but one must use a lot more force. That to me is the difference between the P rated and in my case, D load LT tires.

Be safe.

I have no desire to create any ill will by pursuing this but the idea that same size P tires at the same psi can squish a couple of inches more than an LT is simply not something that happens. Any difference would be a tiny fraction of that. The shape of the load curve (in the normal usage range) for a radial tire of a given size is pretty much the same whether the tire is P or LT. The load curve is based on how much the tire squishes at various load/pressures. A difference of 2 inches, or 1, or 1/2, or even 1/4 would result in two curves that looked very different.

A more apt analogy would be something like an empty plastic water bottle with the cap on. Lay it on its side and put the edge of a 10lb weight on it. It doesn't much matter if the company is now using thinner plastic in an otherwise identical bottle. Its the air providing most of the resistance.

But people are apparently feeling something when they switch to LTs. Side forces are another story, but when that something is being felt in straight line braking and if tire size and pressure haven't changed, (which, when you think about it, is probably rare) I think the stopping distance idea is plausible -- though I don't expect it to gain much....uh, traction.

 

[Jtraskell]

No ill will, I assure you. I was simply stating my opinion of what I THOUGHT might be happening. I know you know a lot more about the science of tires then me. I can only report my experiences, notwithstanding the truth!
Please, do not confuse me with the facts. Let me go on with my fantasy's. To that end, I will be a happier person. That is what we are all striving for, right? Thanks JB. Be safe bud.

 

[philsey]

OK so for S&Gs I went out and aired up from 32 to 40 psi and there is no difference at all except I feel the road more as I am driving... still nose dives as it did with 32... although this may have "some" play in to the nose dive it isnt enough to warrant the cost of new tires.... unless of course you want cooler tires lol I understand the rigidity of the sidewall and compression at stop but I think in the case of the 4R it is 98% suspension related. I would even go further to say shock wouldnt be enough to improve it much I higher spring rate in the coil is most likely the NEED

This is exactly what I did yesterday, and with exactly the same result. I knew I'd not ever drive at 40# but I wanted to determine if the tires squishing were a contributor. Absolutely zero effect on nose dive, pretty dramatic effect on NVH however - unpleasant ride.

Aired down to 35# for the trip home - just less NVH, steering seems a little improved (over 32#). I'll leave it here or at 34#. Agree with Stifler, it's springs, which I'm not interested in fooling with or spending $ on. Done with this.

 

[Ramzey28]

I have no desire to create any ill will by pursuing this but the idea that same size P tires at the same psi can squish a couple of inches more than an LT is simply not something that happens. Any difference would be a tiny fraction of that. The shape of the load curve (in the normal usage range) for a radial tire of a given size is pretty much the same whether the tire is P or LT. The load curve is based on how much the tire squishes at various load/pressures. A difference of 2 inches, or 1, or 1/2, or even 1/4 would result in two curves that looked very different.

A more apt analogy would be something like an empty plastic water bottle with the cap on. Lay it on its side and put the edge of a 10lb weight on it. It doesn't much matter if the company is now using thinner plastic in an otherwise identical bottle. Its the air providing most of the resistance.

But people are apparently feeling something when they switch to LTs. Side forces are another story, but when that something is being felt in straight line braking and if tire size and pressure haven't changed, (which, when you think about it, is probably rare) I think the stopping distance idea is plausible -- though I don't expect it to gain much....uh, traction.

So you felt no difference when you went to c or e load besides maybe a stiffier (bumpier) ride? no difference in cornering? Was it worth giving up p for an lt? (excluding off road purposes)?

 

[JB.]

So you felt no difference when you went to c or e load besides maybe a stiffier (bumpier) ride? no difference in cornering? Was it worth giving up p for an lt? (excluding off road purposes)?

PM sent.