Rough ride - Wheels and Tires - 19.5's to 20" LT's? or Suspension

[java]

OK guys, looking for some input here.

Took the truck out this weekend. This was a first long stretch of gravel we had done, not too bad on the smoother sections but the pot holed areas were brutal. Like 10mph crawl at best, otherwise I thought I would break the truck. This has me thinking about wheels/tires/lift/springs etc. Ill take any input here....

A couple things, these are G rated tires (IIRC!) 14 ply sidewalls. Great on the highway, fine on smooth gravel, ouch in potholes. Has anyone had experience going from a 19.5 tire to a 20" LT? Or too a less load rated 19.5?

Or will a spring change (Kelderman airbags in the front?) make more of a difference? It felt like it was front end for the worst of it....

I dont want to loose the road manner either, as in reality dirt is maybe 20% of our travels.

 

[IdaSHO]

how heavy are you running?

In order to get the softest ride out of TIRES, you need to connect the dots a bit between tire load rating, inflation PSI, and vehicle weight.

Going to a lesser ply-rated tire will result in a better ride. But you need to keep on the positive side of the load ratings, obviously


All that said, if I was concerned about improving ride quality by addressing TIRES, the last thing Id do is go to a larger wheel/less sidewall.

 

[java]

how heavy are you running?

In order to get the softest ride out of TIRES, you need to connect the dots a bit between tire load rating, inflation PSI, and vehicle weight.

Going to a lesser ply-rated tire will result in a better ride. But you need to keep on the positive side of the load ratings, obviously


All that said, if I was concerned about improving ride quality by addressing TIRES, the last thing Id do is go to a larger wheel/less sidewall.

Sorry if I wasn't clear, I'm open to tires or front springs, but tires seem to be the obvious go to first.

I haven't been weighed yet as I was trying to finish the cabinets first. I'm guessing 14-16k ish.

I'm running 5 PSI over minimum inflation to keep the tires seated (no safety beads on 19.5'), 75 psi Front, 80 rear

If I go single I will increase tire size, 37x13.5 most likely, 5" diameter increase, so some sidewall increase.

I was thinking for suspension kelderman airbag spring replacements if I go suspension and keep the tires. (2008 f450 4x4)

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[java]

To bring this back from the dead, I finally got axle weights. Does not look like a single E rated LT is going to cut it. 8040 on the rear axle, and 6200 on the front. Id be running at 100% of load rating basically. Not sure that sounds like a good plan at all...

So I either stick to duals, run a lighter load rated 245 or move to a military/heavy truck tire on a single 20" rim. hmmmm

 

[Bubblegoose1]

Yup, that is where I ended up as well. Frustrating but facts are facts.

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[java]

Yup, that is where I ended up as well. Frustrating but facts are facts.

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I think if I am going to do it, I will do the MPT81's in a 275/80/20 37.4" tall, rated a 4674 lbs each. Its about the smallest "heavy truck" tire I can find. Those with first attack wheels I think would be nice..... But my wallet disagrees!

 

[java]

Ok. I just noticed this post. Let's talk some tire/spring/ride quality basics.

1. Tires do, in fact, have a lot to do with ride quality. However, they do not make the differences that you are thinking about. A large, fat, round tire will give a bouncier ride than a thin, square profiled tire. The distance from the surface of the wheel to the surface of the tire has a direct ratio on ride quality. The bigger the distance, the smoother, yet bouncier the ride. A larger wheel, with a slightly lower profile will give you a harder ride.

2. Wheel size has no bearing on ride quality whatsoever, other than the weight of the wheel (which qualifies as "unsprung" weight) The lower the unsprung weight, the better the ride, handling, and gas mileage.

3. Springs do have a LOT to do with ride quality. You have to understand that the harder the springs, the harder the ride ... however, you need to look at compression ratios for the spring. I think that variable ratio springs tend to ride the best. (It's easy to compress at first, then gets stronger the more you compress it) It's always a give and take. hard spring = better cornering/handling, soft springs=better ride.

I hope this can help your confusion. I would suggest, based on your comments, that you swap out springs, but do some research on it first and be sure what characteristics you prefer. Then buy springs according to your preferences.

Thanks for the reply!

1. Yes, I understand that, I am looking to go to a wheel/tire combo with a softer and larger sidewall. The 19.5 (and 22.5) tires are built with minimal sidewall flex in mind. "Bouncier" is fine, its the harsh impacts from lack of sidewall and sidewall stiffness I am trying to dial down.

2. Wheel size relates to sidewall size in this particular case (if you see what I am saying).

3. yes I completely agree springs have a lot to do with it! I am a couple thousand under GVWR now as it sits, which to me makes me think i am probably close on spring rates (as the OE would spring for the max load, I could be completely wrong here) I highly doubt the Ford used progressive but if they did I would be on the higher rate side with my current load.


As to springs, there are not a ton of options for the 450/550. Kelderman makes an air spring replacement (that I would likely use if I go this route) which gives a tune able spring rate via air pressure. That may be the best place to start I guess, but I also know these tires don't have hardly any sidewall flex or much sidewall size either for that matter. 225/70/19.5

 

[Bubblegoose1]

Thanks for the reply!

1. Yes, I understand that, I am looking to go to a wheel/tire combo with a softer and larger sidewall. The 19.5 (and 22.5) tires are built with minimal sidewall flex in mind. "Bouncier" is fine, its the harsh impacts from lack of sidewall and sidewall stiffness I am trying to dial down.

2. Wheel size relates to sidewall size in this particular case (if you see what I am saying).

3. yes I completely agree springs have a lot to do with it! I am a couple thousand under GVWR now as it sits, which to me makes me think i am probably close on spring rates (as the OE would spring for the max load, I could be completely wrong here) I highly doubt the Ford used progressive but if they did I would be on the higher rate side with my current load.


As to springs, there are not a ton of options for the 450/550. Kelderman makes an air spring replacement (that I would likely use if I go this route) which gives a tune able spring rate via air pressure. That may be the best place to start I guess, but I also know these tires don't have hardly any sidewall flex or much sidewall size either for that matter. 225/70/19.5

What he said ^
Same issue/delimma with my rig. We already know the ins and outs of it. Problem is finding a road worthy change/upgrade. Bottom line 225/70r19.5 is a harsh tire size, with zero air-down potential, to make any difference. Suspension is not the issue; not bottoming out and smooth as glass on regular pavement. Singles can't safely handle the weight. Mine is 13K.

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[java]

What he said ^
Same issue/delimma with my rig. We already know the ins and outs of it. Problem is finding a road worthy change/upgrade. Bottom line 225/70r19.5 is a harsh tire size, with zero air-down potential, to make any difference. Suspension is not the issue; not bottoming out and smooth as glass on regular pavement. Singles can't safely handle the weight. Mine is 13K.

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I'm not quite convinced my front end isn't bottoming out, but I will know next weekend. My truck has 107k on it, I may need some new front springs. (and was thinking possibly moving to f550 ones of not kelderman)

Rear end feels great with 45psi in the air bags. Overloads aren't touching

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[Bubblegoose1]

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[java]

I totally know where you guys are coming from. I was in a similar dilemma and I looked into custom springs. They aren't as expensive as you would think. For a variable spring rate spring it was about $250 each for two, made to order. There are a number of places out there that make them. And for the tires, I don't remember if you said what size tire and wheel combo you have, but you can go with a smaller wheel (I like 17") and use a higher rated tire for the thicker sidewalls. I had a Jeep a number of years ago and I put 17" wheels with E rated tires. So, I had a seriously thick sidewall on a lightweight Jeep. It rode pretty well, but had some stiff springs. You might check with your tire guy and see what he has with that thicker wall. I also contacted the Goodyear Regional Rep. He was more knowledgeable than my local guys.

Yeah custom springs may be an option, it seems springs shops are few and far between these days though.

That the issue, no LT tire can carry the weight of the truck (on the back as a single anyway). Im at 6200lbs on the front axle and 8000 on the rear. I'm at 14240lbs, its not a small truck by any means. I could run dual LT's but that's a whole other issue, not wanting to go there, I would go single before that.

Currently running a 225/70/19.5 front and same with duals in the rear. They are "F" rated at 3970lbs.

I have to run a minimum of 20" to clear the brakes (Maybe some 18" but they would have to be a very thin profile).


Springs may help, especially in the front. Maybe its worth doing the air bag front before wheels and tires....

 

[nick disjunkt]

How about the 11.00r16 Michelin XZL tires? They are not a common size, and may be correspondingly expensive, but in the UK they are load rated to 4806 lb per tire. They are larger than your current tires but they have a much big sidewall.

 

[java]

How about the 11.00r16 Michelin XZL tires? They are not a common size, and may be correspondingly expensive, but in the UK they are load rated to 4806 lb per tire. They are larger than your current tires but they have a much big sidewall.

Exactly similar to what I am looking at, looking at the Continental MPT81 as they come in a little smaller size, its a 275/80/20 (about 10.5r20) I need the larger rim to clear the big *** brakes.

 

[TexomaPowerboater]

Shocks, springs, and new tires would help. The real problem is the front axle design IMO.

 

[java]

Shocks, springs, and new tires would help. The real problem is the front axle design IMO.

Whats so terrible about it? Its been used for years (and yes I dont expect a cadillac ride and know some other MFG's trucks supposedly ride better) and seems to be better than leafs.