No name tires, questions

[aztec7fan]

 So a couple of months ago, we upgraded and purchased a 2003 National Dolphin on the Workhorse W22 chassis. The original tires on it were Michelin XZE 235/80 R22.5 tires, but they were over 14 years old on the date codes. Before driving it from Salt Lake back home to Denver, I insisted we get new tires, and the dealership was able to get me a "deal" on 6 new tires from a local shop. This new size is 275/70 R22.5

These are AR602 PrinX tires. I know, no name, but they ride nice and seem to handle well.

Just wondering if I will encounter problems with the tire size change?

Also, these tires don't have any inflation tables in relation to the vehicle weight, so should I just go by the recommended psi on the coach sticker?

Thanks,
Chris g.

[manholt]

Chris.   How is the clearance between drive tires, no rubbing?  It will effect your speed reading/odometer, less RPM.  Do tires in front scuff on wheel wells when you make a tight turn.  I just looked them up, from Thailand and you'll find the inflation chart under PRIMX Truck/Bus!  They come in 16 sizes!

[richard5933]

I agree with Carl - double check that you have adequate clearance between the duals, but also check that you have adequate clearance on the steer tires when you turn the wheel to both extremes. Your new tires are over an inch wider, so you have to be concerned about interference.

Here's the page for your tires.

http://www.prinxtire.com/product/bus/2020/1111/11.html

[aztec7fan]

Thanks for the replies!  I did check the clearance on the duals, and that looks fine.  I'll have to check the clearance on the steering tires.

I looked over their inflation tables but they don't have any reference for the corner weights on the vehicle, just the max pressure.  In this case, do I just inflate to max pressure? (Their numbers seem suspect too, 900 PSI for a single tire?)

Thanks,

Chris g.

[wildebill308]

1 hour ago, aztec7fan said:

(Their numbers seem suspect too, 900 PSI for a single tire?)

Yes that does seam a bit hi.   What load range are they?

Bill

[aztec7fan]

Load range J.

[rayin]

6 hours ago, aztec7fan said:

Thanks for the replies!  I did check the clearance on the duals, and that looks fine.  I'll have to check the clearance on the steering tires.

I looked over their inflation tables but they don't have any reference for the corner weights on the vehicle, just the max pressure.  In this case, do I just inflate to max pressure? (Their numbers seem suspect too, 900 PSI for a single tire?)

Thanks,

Chris g.

The chart reads in kpa not psi. 900kpa = 130.5psi.  http://www.prinxtire.com/product/bus/2020/1111/11.html

Using the data in the  PrinX link you may now calculate the proper air pressure for your new tires.BUT keep in mind load/inflation charts reflect the minimum air  pressure to support the corresponding load, that means the tire is operating at 100% capacity - no reserve.

Tireman9 recommends adding a 15% air pressure reserve capacity. https://www.rvtiresafety.net/search/label/Inflation

As to a "no name" brand. ALL OTR tires sold in the U.S.A. must meet the minimum requirements of the USDOT/NHTSA

 

Edited April 13, 2021 by rayin

[richard5933]

1 hour ago, rayin said:

...As to a "no name" brand. ALL OTR tires sold in the U.S.A. must meet the minimum requirements of the USDOT/NHTSA

 

Meeting the minimum requirements (self certified, I believe) is one thing. Building a tire which has longevity and reliability in the long run is something different.

[rayin]

1 hour ago, richard5933 said:

Meeting the minimum requirements (self certified, I believe) is one thing. Building a tire which has longevity and reliability in the long run is something different.

Of course you are correct, but as you said tire mfgrs. self-certify, which means we all must depend on tire mfgrs. to always tell the truth. That brings up Michelin RV tire sidewall cracking, Goodyear RV tire rivering, etc. and what actually is the truth about any brand name.

For instance I'm running Sailun truck tires, which according to the mfgr. are constructed the same as Michelin RV/truck tires. The company did move production facilities from China to VietNam in 2017, supposedly to legally avoid the import duties from China and use a completely new truck tire mfg. plant.

Edited April 13, 2021 by rayin

[manholt]

China, I don't want to help support them!  There is nothing wrong with their OTR tires, they depend on moving goods also! Viet Nam?  No thanks!  

[wildebill308]

14 hours ago, rayin said:

For instance I'm running Sailun truck tires, which according to the mfgr. are constructed the same as Michelin RV/truck tires.

What exactly does that statement mean? It is designed to make you think they are  the same quality. All truck tires are made basically the same. Doesn't mean they are made to the same quality. I had Triangle tires on my last RV (they came on it) and they only lasted about 5 years before throwing a tread. I posted about it in Tires.

Bill

 

[rayin]

40 minutes ago, wildebill308 said:

What exactly does that statement mean? It is designed to make you think they are  the same quality. All truck tires are made basically the same. Doesn't mean they are made to the same quality. I had Triangle tires on my last RV (they came on it) and they only lasted about 5 years before throwing a tread. I posted about it in Tires.

Bill

 

That's it, it actually has no legal meaning since every tire mfgr. is self-qualifying for USDOT approval. The only fact I pay attention to is observing the percentage of company-owned OTR trucks running them on steer axles.

[manholt]

Ray, ask Joe, his company run Hankook on all of their OTR's and he has the same on his coach!  

If my current (not my choice) Michelin's last another 2 years or not, I'm going with Hankook also. 

[jleamont]

Hankook and Sumitomo (last company I worked for) BFG, Michelin and Yokohama now. To be completely honest, there is ZERO ride difference and so far no difference in mileage before replacing worth discussing. We get a lot of Michelin excessive vibration at specific speeds which causes us to replace them prematurely. Very frustrating when you spend that much on a virgin steer tire.

[rayin]

I hear you Joe. IMO Michelin is living off the round man era benefits while the world passes them by.

[aztec7fan]

Thanks everyone for the replies and info!  I think I learned more about these inflation tables, but can I verify something?

So if your corner weight is near the max load for the tire, you should inflate to max pressure, but if your weight is at 75% of max load, you should inflate to 75-80% of max pressure?

Is that essentially correct?

Thanks,

Chris

[rayin]

not quite Chris. The air pressure over the correcponding tire load is the MINIMUM acceptable air pressure to  support the load. That means that tire is operating at 100% capacity, no reserve capacity.

As I previously replied Tireman9 recommends adding 10-15% more air to create that tire reserve capacity.

You asked about one tire being very close to maximum capacity; yes ALL tires on that axle should be inflated to sidewall listed  pressure. Never run different air pressure in tires on the same axle.

[manholt]

Ray, if you run the tires at listed SW pressure, how then can you add 10%-15% more air?

Per our weight & 10%, I run 120 on front and 110 on the other 6.  That's cold psi.

[richard5933]

Obviously if one is running their tires at the sidewall pressure there is no way to add an additional buffer. If one needs to run at sidewall pressure to obtain the proper load carrying capacity, then it seems to me either the tires are not up to the take or the coach is too heavy. I'm not an industry expert, but it just seems bad practice to run tires at their rated max load continually without any buffer.

On my previous coach I went up a level in tire load capacity (same size) so that I could run at a lower pressure and leave some capability buffer in the system to avoid running tires at their max load.

[rayin]

4 hours ago, manholt said:

Ray, if you run the tires at listed SW pressure, how then can you add 10%-15% more air?

Per our weight & 10%, I run 120 on front and 110 on the other 6.  That's cold psi.

You're right of course it's one or the other in this specific situation.

 

[aztec7fan]

Rayin, so what are your thoughts on the current axel weights (sorry no corner weights) on my motorhome and the specifications on the Prinx tire chart.  Would you say these tires are under-rated and/or I am over-loaded for these tires given the current weight? Also, at this current weight, my thought is to continue to inflate to max pressure of 130psi.

Thanks for allowing me to keep picking your brain(s).

Regards,
Chris G.

[bm02tj]

It looks like they have miss prints on chart 

they should carry more than your old size tire 

[rayin]

After about 1 hour of study I've determined that Prin load/inflation  chart is so mixed up almost everything I did was a guess at what the author meant vs what they printed.

I recommend you look at tire brands with load/inflation tables that are understandable OR simply run them at sidewall listed pressure.

Not a recommendation only a reference: I run Sailun truck tires, 275/70R22.5 LR H. the  load rating is 6,940 lbs @ 130 psi. I could never do that though, my rims are rated for 120psi.  Sailun does not recommend running less than 80pi., at 80psi the load rating is 5,205lbs on EACH tire. I'm confident other better known brands read about the same.

Edited April 17, 2021 by rayin

[tireman9]

A 235/80R22.5  LR-G (110 psi)  is rated 4675 single  and 4300 dual     Design rim width  6.75  Dual spacing    10.31  (< from Industry chart)

a 275/70R22.5  LR-H (125 psi) is rated would be rated 6940  single   6395 dual  Rim 7.5    Spacing   11.9   (< from GY chart)

Your axle weights are very light!  Are you sure the RV was fully loaded?

I am a bit concerned with rim width and more concerned with dual spacing.  The duals MUST have at lease an inch clearance at the bottom (near road surface).

 

Yes 4 corner weights are hard to get but you can use axle scale reading and assume one end of the axle is supporting 52% of the load.  Use that load to check the tables to learn the MINIMUM inflation needed.   Add 10% to that Minimum with 15% inflation margin being better.

 

Hope this helps

[aztec7fan]

52 minutes ago, tireman9 said:

A 235/80R22.5  LR-G (110 psi)  is rated 4675 single  and 4300 dual     Design rim width  6.75  Dual spacing    10.31  (< from Industry chart)

a 275/70R22.5  LR-H (125 psi) is rated would be rated 6940  single   6395 dual  Rim 7.5    Spacing   11.9   (< from GY chart)

Your axle weights are very light!  Are you sure the RV was fully loaded?

I am a bit concerned with rim width and more concerned with dual spacing.  The duals MUST have at lease an inch clearance at the bottom (near road surface).

 

Yes 4 corner weights are hard to get but you can use axle scale reading and assume one end of the axle is supporting 52% of the load.  Use that load to check the tables to learn the MINIMUM inflation needed.   Add 10% to that Minimum with 15% inflation margin being better.

 

Hope this helps

Thanks tireman.  I have checked the spacing in the duals, and they look "ok", but I can't confirm if it's a full inch.  I'll have to measure it this weekend.

The Rv was loaded for a short weekend trip.  The fresh water and holding tanks were all about 1/3 full, and fuel was full.  Most of our usual "stuff" was loaded, so I would say the weight was typical of most of our trips.