New Maxxi's 15" Load Range E tires. Wheel question?

[therink]

I just ordered a new set of Maxxis 10 ply load range E tires to replace my factory set of Towmax load range D rated tires. Both are 225 75R15. I am planning on keeping the OEM 15" aluminum wheels, but am not sure if they can handle 80 psi with the new tires. The d rated tires ran at 65 psi.
Anyone know if the factory 15" wheels can handle 80 psi or not?
Steve

[JRTJH]

The max load and max PSI should be stamped on the back side of the wheel. Crawl under the RV and look (or check your spare if it's the same type wheel)

[geo]

Steve -

It is the air pressure in the tire that supports the weight of the vehicle, not the tire itself. If you are replacing the D load range tires with E load range, then you need to inflate the tires as if they were D - 65 psi. The "rating" on the side of the tire is the "maximum pressure" for the tire. You should use the recommended tire pressure as referenced by Keystone.

Basically, it works out in the following manner. If you were to measure a single tire's contact with the "ground", you might find that the tire "footprint" is 6" wide and 7" long (yes, I'm making these numbers up since I don't know the footprint measurements of your tires). That means that your tire contacts the ground with 42 sq. in. At 65 psi, that would be 45 x 65 = 2925 pounds - that is the weight that tire can carry. Now, if you run that up to 80 psi, then you might have a problem. For one, the tire would "balloon", it would not have contact with the ground across the tread width, rather it would have an elliptical ground contact and thus wear the center portion of the tire unevenly. Otherwise known as "over-inflated". Working the math backwards, if your tires supported the 2925 pounds each (5850 pounds per axle), then that elliptical contact would have 36.6 sq. in. If you get, or look up, the Maxxis inflation table for your new tires, you will probably find that your new E load range tires have an inflation rating for the D load range - 65 psi.

So, whether the factory 15" rims can handle 80 psi or not is really not an issue. You want to treat the E load range tires as if they were D load range for inflation. And as you travel down the road, you will know you have "plys to spare" to carry your RV. :D

Ron

[hankpage]

More plys + more road contact = more rolling resistance = more heat = tire failure ...... What is the sense of using E rated tires if you are going to try to make them Ds. (Like buying a V8 engine and pulling two plugs because you only need a V6) A good tire shop will not mount the tires on the wrong rated rims with the wrong valve stems. The correct rims + the manufacturers recommended inflation pressure for your GVW will = a happy camper. JM2¢, Hank .....Ron , This probably the first time that I have had to disagree with you. Hank

[therink]

More plys + more road contact = more rolling resistance = more heat = tire failure ...... What is the sense of using E rated tires if you are going to try to make them Ds. (Like buying a V8 engine and pulling two plugs because you only need a V6) A good tire shop will not mount the tires on the wrong rated rims with the wrong valve stems. The correct rims + the manufacturers recommended inflation pressure for your GVW will = a happy camper. JM2¢, Hank .....Ron , This probably the first time that I have had to disagree with you.

Hank

I still have not confirmed what my rims are rated for (psi). I was hoping someone with the common late model 15" aluminum keystone wheels would chime in to confirm.
I hope I'm not going to be forced to buy wheels as well.

[hankpage]

I still have not confirmed what my rims are rated for (psi). I was hoping someone with the common late model 15" aluminum keystone wheels would chime in to confirm.
I hope I'm not going to be forced to buy wheels as well.

Keystone buys in bulk and your rims may not be the same as someone else's. My Steel rims were not rated for load range E but I have heard of others with aluminum rims that were. If yours are be sure to get the proper valve stems installed. My rim rating was stamped inside the rim under the bead. (Brilliant)

[geo]

More plys + more road contact = more rolling resistance = more heat = tire failure ...... What is the sense of using E rated tires if you are going to try to make them Ds. (Like buying a V8 engine and pulling two plugs because you only need a V6) A good tire shop will not mount the tires on the wrong rated rims with the wrong valve stems. The correct rims + the manufacturers recommended inflation pressure for your GVW will = a happy camper. JM2¢, Hank .....Ron , This probably the first time that I have had to disagree with you. Hank

Hank,

I understand. Actually, Goodyear has some very good reference links on this topic on their ST tire website (http://www.goodyearrvtires.com/tire-inflation-loading.aspx). More plys do not necessarily mean more road contact. The road contact is actually dictated by the inflation of the tire and the weight of the vehicle (RV in this case). For example, if you have one tire that should have 65 psi, but is low and has 45 psi - it will "look" under-inflated. That means it will have more contact with the "ground" to support the weight. And the low tire means it will be contacting the "ground" improperly and will have problems.

If you get into looking at this, you will find "Load Range" is a bogus term. Some tire manufacturers give a "Load Range" with a 10% safety factor, while others give a "Load Range" with a 20% safety factor. That is why Power King TowMax tires have a 3420 pound @ 80 psi capacity at Load Range E (10% safety factor) while the Michelin XPS has a 3042 pound @ 80 psi capacity at Load Range E (20% safety factor). Do the math and you will find that each has a non-safety rating of 3800 pounds.

Though it is very hard to find, what the REAL tire weight bearing figure that I wish we could all have on our tires is the Load Index Number. That is the figure and table that should actually be used, and this whole letter load range should be dropped.

Personally, I have switched my own tires on my Alpine away from the Power King TowMax Load Range E tires. Yup, this could start the whole "tire wars" all over again! :eek: So, let me state this is a personal choice! I have switched those tires for the Goodyear G614 Load Range G. If one examines the Goodyear Inflation Table: http://www.goodyearrvtires.com/pdfs/rv_inflation.pdf, one will find these G614 tires have a Load Range E inflation entry (80 psi). And even a Load Range D inflation entry of 65 psi.

So, Hank, it is your right to disagree with me. I take no offense and am pleased that you do. However, from my own research and thoughts, I do have to disagree with you, please take no offense. But you might find some of the information on the Goodyear website interesting, along with several other websites you can search.

Oh, I will say that with the new G614s on the Alpine, on our trip the past two weeks to southern Colorado, the G614s were running about the same temperature as the TowMax did on our trip to Tennessee/Kentucky last year. Even between Wichita Falls and Amarillo! (One boring drive!!!)

Ron

[biglake]

Thinking about putting 16 inch tires and rims on raptor 3612 have not heard anything good about 15 inch tires, 500 more dollars to buy rims also hate to waste money on 15 inch tires if they are gonna blow out and cause trlr damage. looking for opinions. Thanks Mark

[geo]

Thinking about putting 16 inch tires and rims on raptor 3612 have not heard anything good about 15 inch tires, 500 more dollars to buy rims also hate to waste money on 15 inch tires if they are gonna blow out and cause trlr damage. looking for opinions. Thanks Mark

BigLake -

Jim W. has excellent advice about the distance between tires - see: http://www.keystonerv.org/forums/showthread.php?p=43484#post43484 When you switch rim size, you will also cause a difference between the distance between the tires. The axles are fairly well fixed at their distance apart - way too much welding involved to change that distance! So, changing the rims should be approached with great caution!

Ron

[biglake]

Thanks Ron I put borrowed tires and wheels on trlr yesterday had over 1 inch between tires and 3 to five fingers of clearence on top of tires with trlr weight on axels, wondering if that will work thanks Mark

[geo]

Thanks Ron I put borrowed tires and wheels on trlr yesterday had over 1 inch between tires and 3 to five fingers of clearence on top of tires with trlr weight on axels, wondering if that will work thanks Mark

Mark -

If that is the case, measure the distance between the frame and the axle leaf springs at normal trailer weight. If that distance is less than the distance you measured between the top of the borrowed tires and the bottom of the trailer, I think it should be just fine. Wait a day or two to see who else comments and their opinion.

Ron

[springfield5]

I still have not confirmed what my rims are rated for (psi). I was hoping someone with the common late model 15" aluminum keystone wheels would chime in to confirm.
I hope I'm not going to be forced to buy wheels as well.

Hi,

I have these wheels on my 2012 Cougar but am not certain of the style that you have. They are reated for 2830lbs at 80psi.

http://www.etrailer.com/question-37537.html

I also ordered Maxxis Load E tires so I checked out the wheels for the capacity. I will install the TR600HP valve stems as well...rated for 100PSI. I hope this helps and good luck with your search!

[CWtheMan]

I just ordered a new set of Maxxis 10 ply load range E tires to replace my factory set of Towmax load range D rated tires. Both are 225 75R15. I am planning on keeping the OEM 15" aluminum wheels, but am not sure if they can handle 80 psi with the new tires. The d rated tires ran at 65 psi.
Anyone know if the factory 15" wheels can handle 80 psi or not?
Steve

Boy oh Boy, I could post in this thread all day on all the disinformation being passed out. But, I’ll stick to the issue posted by the OP.

Because there are so many safety issues with tires, more and more information is being molded right into the tire’s caucus for the owner to read. Here is an example that tire installers need to follow.

http://www.irv2.com/photopost/showfull.php?photo=20708

Somewhere on your rims you will find it’s load capacity or maximum pressure rating. The manufacturer does not have to put both - although some do - because one is synonymous with the other.

By going up a load range with your tires you have done what is referred to as “plus sized” them. In most cases that requires a new “recommended tire pressure” to be applied to them. With ST tires it’s more complicated because ST tire manufacturers set different operating parameters on like sized tires. Maxxis is one of the very few ST manufacturers that allow their tire’s air pressures to be manipulated with their load inflation table. In your case you can run the LRE tires at the placard pressure of 65 psi because it meets the vehicle manufacturers minimum load capacity at that pressure. However, all ST tires are designed to be run at full sidewall pressures. And, you gain nothing with LRE over the LRD by not increasing the tire pressure to take advantage on the reserve load capacity protection the LRE will give you.

A foot note: Maxxis only allows manipulation of their ST tire pressures via their load inflation table with the approval of the vehicle manufacturer. For verification of that statement you can call Mr. Shaun Brennan at 678-407-6772. He is an area representative for Maxxis tires here on the east coast.

CW

[therink]

Boy oh Boy, I could post in this thread all day on all the disinformation being passed out. But, I’ll stick to the issue posted by the OP.

Because there are so many safety issues with tires, more and more information is being molded right into the tire’s caucus for the owner to read. Here is an example that tire installers need to follow.

http://www.irv2.com/photopost/showfull.php?photo=20708

Somewhere on your rims you will find it’s load capacity or maximum pressure rating. The manufacturer does not have to put both - although some do - because one is synonymous with the other.

By going up a load range with your tires you have done what is referred to as “plus sized” them. In most cases that requires a new “recommended tire pressure” to be applied to them. With ST tires it’s more complicated because ST tire manufacturers set different operating parameters on like sized tires. Maxxis is one of the very few ST manufacturers that allow their tire’s air pressures to be manipulated with their load inflation table. In your case you can run and the LRE tires at the placard pressure of 65 psi because it meets the vehicle manufacturers minimum load capacity at that pressure. However, all ST tires are designed to be run at full sidewall pressures. And, you gain nothing with LRE over the LRD by not increasing the tire pressure to take advantage on the reserve load capacity protection the LRE will give you.

A foot note: Maxxis only allows manipulation of their ST tire pressures via their load inflation table with the approval of the vehicle manufacturer. For verification of that statement you can call Mr. Shaun Brennan at 678-407-6772. He is an area representative for Maxxis tires here on the east coast.

CW


This is great information. I am going to tire place in about an hour. I will be onsite during the tire install and will verify the wheel capacity. I will let you know how I make out.
Steve

[therink]

I am just had the Maxxi's E's installed. Had it done at Pep Boys. They had no idea how to jack up the trailer so. I got out my bottle jacks and did it for them. I'd rather do it anyway. I looked at the ratings inside one of my wheels and it says max load 2,880 lbs. It said nothing about max psi. I had them balanced and filled to 80 psi. I compared the two unmounted tires and what a difference. The Maxxi must have weighed 5 lbs more. It is ridiculous how thin and cheesy the side wall was on the Towmax. The Maxxis sit so much better/stout under load on the trailer.
I am a happy camper and think I will enjoy pulling the trailer with a bit more confidence? I will spend more time watching the road than staring in the mirrors at the tires.
Thanks everyone for the input.

[Handysam]

Yup, new Maxxis tires here as well, and very pleased so far. Curious where you jacked up your camper, that's a whole new can of worms and opinions. Happy Camping, Sam

[kenn209]

I went through this last year, but still have the Towmax, Gonna change them out this next year, Anyway I emailed the Cougar rep and asked about the wheels, They get them from Tredit. http://www.tredittire.com/ So I emailed them about the specific wheel that came on the trailer and they told me the wheel is rated to 80psi. I have the T03 wheel on the website. Hope this helps.

[therink]

Yup, new Maxxis tires here as well, and very pleased so far. Curious where you jacked up your camper, that's a whole new can of worms and opinions. Happy Camping, Sam

We jacked one side at a time using one floor jack and one bottle jack under each of the axle u bolts. Placed a piece of wood between jacks and u bolts to spread and even the load. There was no issues doing this.

[therink]

I went through this last year, but still have the Towmax, Gonna change them out this next year, Anyway I emailed the Cougar rep and asked about the wheels, They get them from Tredit. http://www.tredittire.com/ So I emailed them about the specific wheel that came on the trailer and they told me the wheel is rated to 80psi. I have the T03 wheel on the website. Hope this helps.

I'm glad the wheels are rated at 80, because that's what I'm running now. Thanks for confirming that.

[matthewc45]

I just had a set of these put on my Springdale and would have to say by far the best choice I could have made. Just got back from the first trip out with the tire and the camper road smother than befor. I also have aluminum rim on mine they hold the psi fine.

[hankpage]

Steve, I'm glad things worked out in your favor. But, Did they replace your valve stems to upgraded pressure and torque your wheels correctly?? (Can you tell I have very little faith in discount auto parts shops?) Now that you have towed it a little, Check the torque on your rims as per Keystone's instructions and enjoy your new-found piece of mind. Hank