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Old 07-19-2016, 03:22 PM   #15
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The OP can not get any meaningful answer until he weighs each wheel position. Until then it's just a cap shoot. With the weights, a good solution can be attained.

FWIW. It might not mean much, but by weighing my Avalanche and keeping the pressures where they need to be, I get 80,000 miles on the original tires before I replace them.
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Old 07-19-2016, 07:43 PM   #16
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OK... well, it looks like I've put the proverbial cart before the horse yet again. After looking up some specs I have to admit I've made a couple mistakes with some of the information I've posted.

First of all my duals are not 2/3's worn. They are approximately half worn. The duals measure around 9/32 down to 7/32 depth at the shallowest part. I had thought the original tread depth was 16/32,but when I looked it up... Nope... It was 13/32. If you use the 3/32 wear markers as considered worn out then right now the tires are basically half gone at 20,000 miles... maybe a little less than half gone if I rotate them to try and correct the extra wear on the outer dual.

Secondly... The unladen weight of 18,500 that I posted before might be wrong. The only place I can find that figure is on the PA title, and I don't trust anything the state of PA puts on anything. I found a scale located nearby, and hopefully this weekend I can find time to go and at least measure the axle weights. I'm guessing it might weigh a bit less than 18,500... it still seems light in the front though.

The tag on the rv gives the following info:
  • GVWR: 19840
  • GAWR Front: 6340
  • GAWR Rear: 13,500
  • GCWR: 25,000
  • Tires Front: 8R19.5 80 psi
  • Tires Rear: 8R19.5 90 psi
  • (note that tires on RV are actually 225 70R19.5's)
Question: The 95 psi column in the chart below shows the max cold psi rating that is found on the sidewall of my tires (second row in the chart)... and yet there are several columns beyond that up to 110 psi... can the tires be taken beyond 95 psi cold?

At the end of the day... the tires do seem to be wearing just slightly like they're under inflated. You can't see the difference in wear... you actually have to measure it. There might be 1/32 difference from the center to the edges. It's not much... some of that could just be measurement error, or just how duals wear? I don't know much about all this... so maybe the tires really aren't overloaded? I guess I won't know for sure till I get some axle weights. Ok... I'll shut up till i have those numbers.

I think my tire gages are good... I have a nice dial type and also a stick type... they both read the same.

Maybe I'm being silly about all this... but if there's anything I can do to extend the life of my tires, I'll certainly do it.

-cheers


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Old 07-19-2016, 08:55 PM   #17
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If you look at the inflation chart you will see 95 psi is the max for an "F" rated tire. The psi goes higher up to 110 psi for the "G" rated tire. You say you have the "F" so 95 is the max cold psi.

edit: Also note that your "F" rated size has a slightly higher carrying capacity @ 95psi than the stock 8R19 tire @110 psi
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Old 07-19-2016, 09:05 PM   #18
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Our 450 pulled a KZ 41 (18,000 lbs). We have 75,000 on the 19.5 tires and they can go farther but will be replaced because of age.


Sounds like something is amiss. Likely tire pressure. Is it possible the rear axle is bent?
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Old 07-20-2016, 04:30 AM   #19
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If you look at the inflation chart you will see 95 psi is the max for an "F" rated tire. The psi goes higher up to 110 psi for the "G" rated tire. You say you have the "F" so 95 is the max cold psi.
Okay that makes sense...

Gordon, As far as the axle being bent... I don't think so? I suppose anything is possible though. There's no apparent damage underneath... the springs are in good condition... it passes PA state inspection every year. I do know it drives pretty straight down the highway. It's not like I have to fight it to keep it on the road. Just point and go.

I do check the tire pressure regularly... Pretty much before every leg of a trip. I've never had to adjust tire pressure on the road, but I do carry a little pancake type air compressor that's good to 130 psi just in case.

On a positive note... thinking I might get 40k out of a set of duals is better than 30k. Still doesn't seem to be what others are experiencing though... Like someone said early... I probably need to get it weighed before any meaningful discussion can really be had. I really should have done that a long time ago...

-cheers
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Old 07-20-2016, 04:49 AM   #20
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Well that's what I was thinking after hearing all the hubub about rv tires going bad from age long before wear. Maybe it's all the burnouts and wheelies I'm doing?

In all seriousness... I'm wondering what the deal is here. Again... is there a difference between 22.5 tires and 19.5 tires as far as wear? Bigger... less rotations to go the same distance... and maybe made from harder stuff? I don't know... if there was a way to get more miles out of mine... or if I need to change something I'm doing something terribly wrong... I'd do it!

-cheers
On my Peterbilt, pulling a 53' Reefer, and with 22.5 tires, I get between 200,000 and 300,000 miles on the tires. I keep the pressures spot on, have them balanced, and use centrmatics for active balancing. I also rotate once or twice in that mileage.
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Old 07-20-2016, 06:23 AM   #21
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I had the Goodyear 19.5 G670 with about 20,000 miles on our 2008 Damon Challenger 378. I replaced them because the outside edges on both the inner and outer part of the front tires were wearing at a rapid pace all 4 rear tires were showing signs of the same ware pattern. From what I read Goodyear RV tires were doing this and it was called RVing. I kept the tires inflated to the proper pressure. I replaced them with TOYO tires and have put about 20,000 miles on them and they show no sign of ware on the outside edges so I will have to see how far I can go. But for safety I wll be replacing them after 9 to 10 years no matter how low the mileage .
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Old 07-20-2016, 07:18 AM   #22
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Piker, look at the rims. You said the original tires were 8R19.5, which call for a 6" wide rim, and you are now running 225 75 r19.5 tires that call for a 6.75" wide rim. Too narrow rims will cause the tires to wear unevenly.
Glad to see you have all of the big projects out of the way and are now worrying about the small stuff☺
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Old 07-20-2016, 08:33 AM   #23
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Piker, look at the rims. You said the original tires were 8R19.5, which call for a 6" wide rim, and you are now running 225 75 r19.5 tires that call for a 6.75" wide rim. Too narrow rims will cause the tires to wear unevenly.
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Old 07-20-2016, 11:52 AM   #24
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Piker, look at the rims. You said the original tires were 8R19.5, which call for a 6" wide rim, and you are now running 225 75 r19.5 tires that call for a 6.75" wide rim. Too narrow rims will cause the tires to wear unevenly.
Glad to see you have all of the big projects out of the way and are now worrying about the small stuff☺
Good catch. I'll have to measure them.

But...

Wouldn't a rim that is too narrow cause the wheel to wear more in center though? The additional wear I'm seeing is at the edges.

-cheers
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Old 07-20-2016, 03:53 PM   #25
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I couldn't stand the suspense, so I said to heck with work this afternoon and took the RV over to have it weighed. The RV was empty... except for me and 160lbs (20 gallons) of water in the potable tank. Black and gray tanks empty. Diesel fuel tank full. Granted... I don't have numbers for when we're loaded up, but at least I have a starting point. The front is not as light as I had thought it might be...

Rear axle: 12,960
Front axle: 6,080
Grand Total: 19,040 (remember the gvwr is rated @ 19,840... no doubt in my mind that we're overweight when loaded up)

I run duals at 95 psi and steer tires at 90 psi.

According to the chart:
The duals... at 95 psi... are good to 13,660
The steers ... at 90 psi... are good to 6,900
Total Tire capacity: 20,560

If everything were loaded in a balanced manner, this would give me 1500 lbs for "stuff" and people as far as the tires are concerned. That's probably not quite enough for us, especially on our last trip with 6 people in the RV... but for just the 4 of us... it's probably close. Again... I can't say for sure without actually weighing it fully loaded, but we're not planning any more extended trips this year...

Some notes on the tanks: Potable tank (60 gallon) is just about centered between the front and rear axles... but both the gray and black tanks are well behind the rear wheels. Fuel tank (90 gallon) is forward of the center of the wheel base - right behind front axle.

I'm thinking the front tires at 90 psi are pretty close to where they should be once we're loaded with people and stuff.

At 95 psi, the rear tires are probably slightly overloaded, especially once the water from the potable tank has been transferred to the waste tanks... But I think it's still kind of in the ballpark.

At this point, if I'm interpreting this correctly... it looks like the little bit of extra wear I'm seeing on the outside of the duals could indeed be caused by this slight overloading.

But...

I think the bigger issue here is the OVERALL wear. There's no way in heck I get 70,000 out of these. I'll feel lucky to get 35/40k.

Thoughts? Am I missing something?

PS... duals on right are wearing the same as duals on left...

-cheers
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Old 07-20-2016, 04:30 PM   #26
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Originally Posted by Piker View Post
I couldn't stand the suspense, so I said to heck with work this afternoon and took the RV over to have it weighed. The RV was empty... except for me and 160lbs (20 gallons) of water in the potable tank. Black and gray tanks empty. Diesel fuel tank full. Granted... I don't have numbers for when we're loaded up, but at least I have a starting point. The front is not as light as I had thought it might be...

Rear axle: 12,960
Front axle: 6,080
Grand Total: 19,040 (remember the gvwr is rated @ 19,840... no doubt in my mind that we're overweight when loaded up)

I run duals at 95 psi and steer tires at 90 psi.

According to the chart:
The duals... at 95 psi... are good to 13,660
The steers ... at 90 psi... are good to 6,900
Total Tire capacity: 20,560

If everything were loaded in a balanced manner, this would give me 1500 lbs for "stuff" and people as far as the tires are concerned. That's probably not quite enough for us, especially on our last trip with 6 people in the RV... but for just the 4 of us... it's probably close. Again... I can't say for sure without actually weighing it fully loaded, but we're not planning any more extended trips this year...

Some notes on the tanks: Potable tank (60 gallon) is just about centered between the front and rear axles... but both the gray and black tanks are well behind the rear wheels. Fuel tank (90 gallon) is forward of the center of the wheel base - right behind front axle.

I'm thinking the front tires at 90 psi are pretty close to where they should be once we're loaded with people and stuff.

At 95 psi, the rear tires are probably slightly overloaded, especially once the water from the potable tank has been transferred to the waste tanks... But I think it's still kind of in the ballpark.

At this point, if I'm interpreting this correctly... it looks like the little bit of extra wear I'm seeing on the outside of the duals could indeed be caused by this slight overloading.

But...

I think the bigger issue here is the OVERALL wear. There's no way in heck I get 70,000 out of these. I'll feel lucky to get 35/40k.

Thoughts? Am I missing something?

PS... duals on right are wearing the same as duals on left...

-cheers

Piker,

I have enormous respect for you, your attitude and all you have accomplish with your coach.

Remember, the pressures on the chart is the lowest pressure to carry that weight level. If it were my coach, I would pump up the drive tires from 95 to 105. That might slow the wear back there. That's also where lots of your travel weight will be added. You could leave the steer pressure where it is or bump it up to 95.

Have you checked your ride height? That could also affect tire wear and quality of the ride.

Good luck with sorting it all out.
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Old 07-20-2016, 05:07 PM   #27
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This is a question for those who actually wear tires out from use BEFORE they are worn out from age. I'm not interested in the typical back and forth banter about "old" tires.

How many miles do you get out of a set of tires before the tread is gone?

I'd like to compare:
  1. Rig weight
  2. Toad/No-Toad
  3. Tire specs
  4. Whether or not you rotate tires
  5. Expected mileage per set of tires




-cheers
Rig: 2013 F53 18,000 GVWR - Actual Loaded Weight 5620 front, 10260 rear
Toad: 2013 Chevy Sonic
Tires: G670 24570R19.5G
Rotation: None
Expected Tire Life: Tread depth now 9/32 all around (40% worn) after 27,000 miles so expected tire life is 67,500 miles.

Question: the G670's say "re-groovable" on the sidewall. Has anyone ever had that done? Is it worth it?
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Old 07-20-2016, 06:05 PM   #28
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Piker,

If it were my coach, I would pump up the drive tires from 95 to 105.

Have you checked your ride height? That could also affect tire wear and quality of the ride.
Can I raise the pressure above 95 on this tire with an F load range? Says 95 psi max cold on the sidewall...

I was thinking maybe the RV should actually have G rated tires so I can go the extra 5 or 10 psi in the duals?

I have no idea what you mean by ride height? Are you thinking we have air suspension? We don't... Regular old shocks and springs... and hydraulic brakes. FYI... no exhaust brake either... really wish I had one... could really have used it in the mountains of Montana and Wyoming on our last trip.

Oh and thanks for the compliment... you are too kind...

-cheers
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