Maxxis Tires Speed Rating - Mfg's Statement

[Tireman9]

"Rarely is any tire needing to run at max pressure on the side wall of the tire. That is the pressure for the max loading on the tire, and it is not common for folks to have a a gross that is the max the tire was designed to run."

Tires in multi-axle trailer application can lower the "Interply Shear" forces that are the basis for most belt separations, by running higher inflation pressure than needed based on weight scale reading.
RV Tire Safety: Question on Interply Shear on trailer tires vs tow vehicle tires

"R&D on most of our tires are a collaboration between the tire builder and the builder of the vehicle they are to be fitted to."

While this is true for automotive & LT applications where individual tire specifications are selected after extensive on vehicle evaluations, I have never heard of an RV company working with a tire manufacturer on the selection or tuning of a tire specification.


Most car applications have certification label inflations that are lower than the "maximum" inflation number on the tire sidewall.

All passenger cars and LT vehicles and most heavy truck vehicles for normal highway use, are built to and must comply with FMVSS regulations. I know of no exceptions.

"Differing brands of trailer tires, meant for similar uses, do not always have the same inflation recommendations from the tire maker."

Vehicle Certification labels or "Tire Placards" have inflation levels specified by the RV company. Tire manufacturer has no responsibility in the selection of the inflation level for that specific application.

"Run the tire at max cold pressure and you should be within all safety margins as long as you keep the speed and weight within what is on the tire. You do not have to reduce max load beyond "x" speed unless the manufacturer has otherwise stated it on the side of the tire."

Sorry, not correct. There are numerous specifications and requirements covered in US Tire & Rim Association guides as well as in tire company "Data Books" that address speed, load and inflation limits and adjustments. One clear example is the 75 mph max speed for tires in RV application. This limit is in Goodyear, Michelin and Bridgestone data books.
If you have an example of a tire with speed and different loads or inflations on the sidewall I would be VERY interested to see a pictrue as that would be a first for me as a tire engineer with 40 years experience.

"A tire overinflated for the load will hydroplane more quickly and there is also a reduction in effective braking capability. It could also be argued that cornering ability is diminished with over inflated tires. There needs to be the proper "foot print" of the tire on the road surface, and overinflation for the load negatively affects that foot print." is an over simplified claim. There are many times where higher inflation will improve handling. This is based on my personal experience as a professional race car driver. "Overinflation" is not a well defined word but simply having more pressure than the tables suggest for a given load is by no means always a bad thing to do. We need to be more specific. Are you talking about a +10% inflation or + 50% inflation level?

[Wileykid]

Originally Posted by Tireman9

Sorry, not correct. There are numerous specifications and requirements covered in US Tire & Rim Association guides as well as in tire company "Data Books" that address speed, load and inflation limits and adjustments. One clear example is the 75 mph max speed for tires in RV application. This limit is in Goodyear, Michelin and Bridgestone data books.
If you have an example of a tire with speed and different loads or inflations on the sidewall I would be VERY interested to see a pictrue as that would be a first for me as a tire engineer with 40 years experience.

Thanks for the links. Very informative, and the learning continues with the knowledge imparted by several of the members.

But, using the links you have provided, Goodyear shows the Endurance speed as max of 87 mph (https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf). So where is the info that limits the tire to 75 mph? I could not find that on the Goodyear site. If you are referring to the tire-care-guide (https://www.goodyearrvtires.com/pdfs...care-guide.pdf), that was printed in 2010 and does not cover the Endurance line.

Mark

[Tireman9]

Originally Posted by Wileykid

Thanks for the links. Very informative, and the learning continues with the knowledge imparted by several of the members.

But, using the links you have provided, Goodyear shows the Endurance speed as max of 87 mph (https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf). So where is the info that limits the tire to 75 mph? I could not find that on the Goodyear site. If you are referring to the tire-care-guide (https://www.goodyearrvtires.com/pdfs...care-guide.pdf), that was printed in 2010 and does not cover the Endurance line.

Mark

The GY RV data book shows 75 as the max speed for all their other tires. Many of which have higher speed symbol higher than 75 but GY like Michelin and Bridgestone limit RV application speeds to 75.
You can find links to many trie company tables and data books on my Blog. I try and keep the links up to date and the GY link was updates this month. Yes the data book does not yet have Endurance but you will find the LTX line with a stated 75 max even though the LTX line has higher symbol on the tire.

Data book takes priority over tire sidewall except for load & inflation info.

[Airdale]

Originally Posted by Tireman9

The GY RV data book shows 75 as the max speed for all their other tires. Many of which have higher speed symbol higher than 75 but GY like Michelin and Bridgestone limit RV application speeds to 75.

Than the vehicle manufacturer should say so in the vehicle owner's manual. I'm just saying' you know, speed letters or other speed indicator markings on a tire's sidewall are official unless otherwise stated in an official governing body way.


You can find links to many trie company tables and data books on my Blog. I try and keep the links up to date and the GY link was updates this month. Yes the data book does not yet have Endurance but you will find the LTX line with a stated 75 max even though the LTX line has higher symbol on the tire.

Data book takes priority over tire sidewall except for load & inflation info.

What type of priority do you refer? If industry wide it would be common knowledge and not in some data book. Is it about specific tires that other's do not build? Carlisle recommends 60 mph for their trailer tires but build them with much higher speed letters.

Tire manufacturer's, like the TRA, have confidential stuff they don't print. How much of that stuff can you print without someone tapping on your shoulder?

It's sort of like Maxxis saying their ST tires have a speed rating equal to the letter "Q". But saying it just don't cut it. It's not a word of mouth industry. We need certified proof and that's what the DOT symbol on the tire is mostly all about. If TRA wanted every Tom, Dick, Harry & Jane to know all about their workings they would get out from behind their confidential umbrella and publish a "need to know" document.

A number of years ago Michelin ventured into the RV trailer industry with some 17.5" European designed low platform trailer tires for those heaviest of RV trailers. Problem is, those tires were LRJ and had a speed letter rating "J" = 62 MPH. The RV trailer manufacturer set the recommended inflation pressures at max. Michelin said with weight and inflation pressure manipulations the speed could be increased. RV trailers are built to FMVSS standards that won't allow that to happen. No more OEM Michelins of that size designation and load range.

[Wileykid]

Originally Posted by Tireman9

The GY RV data book shows 75 as the max speed for all their other tires. Many of which have higher speed symbol higher than 75 but GY like Michelin and Bridgestone limit RV application speeds to 75.
You can find links to many trie company tables and data books on my Blog. I try and keep the links up to date and the GY link was updates this month. Yes the data book does not yet have Endurance but you will find the LTX line with a stated 75 max even though the LTX line has higher symbol on the tire.

Data book takes priority over tire sidewall except for load & inflation info.

Again, I am having trouble with your logic. Just because one tire is limited to "x" speed even with the higher speed symbol, doesn't mean that is applicable to another without published proof. Best I can tell, you are using a table that was published in 2010, which means the tire (LTX) was designed several years prior to that. Saying that a tire that is at least 6-8 years newer in design, materials, model number, and has a table that was published in 2017 showing the higher speed corresponding with the speed symbol on the tire is wrong. As a matter of fact, the same table shows the Endurance at 87 mph, and the G670 RV® as 75 mph.

Look, you have a pretty good blog, but you are making assumptions without proof. Basing it on an older and/or different tire design is wrong. Please show the evidence saying that the Endurance tire is limited to 75 mph, and what Goodyear has published for the public to use and go by is wrong.

I am not trying to pick a fight with you, but after a 30+ year career in aviation, I go by what the manufacturer says, not someone telling me jeez, don't believe those numbers, they are wrong and here are the correct ones.

Mark

[Mad Cow]

I keep things simple. I rarely run over 65 mph, towing or not.

[Arctic Wolf]

Originally Posted by Mad Cow

Rarely is any tire needing to run at max pressure on the side wall of the tire. That is the pressure for the max loading on the tire, and it is not common for folks to have a a gross that is the max the tire was designed to run.

On my semi truck tires, the max on the sidewall is 120 PSI. But The recommended pressure from the tire maker based on the max load of my axles is 95 PSI. I have averaged 400,000 miles on drive tires following the guidelines from the tire OEM.

Same thing for the BFG KO2's on my 3/4 ton pickup. The vehicle OEM recommended pressure is when the pickup is at max gross and the brand and type of tire from the factory. I ignore that. I have a chart from BFG for the exact tire I am running that shows recommended pressure based on weight on the axles.

If one wants, they can usually pry a recommended load pressure chart from the tire OEM for the particular tire they are running and stick to it. In my experience, following the guides makes for better handling, braking, and tire wear.

But everyone seems to know more than the folks who actually did the R&D on the tire.

What kind of mileage are you getting from the KO2s? I'm running them on my F250 and at about 30k it's time for new tires

[Mad Cow]

Originally Posted by Arctic Wolf

What kind of mileage are you getting from the KO2s? I'm running them on my F250 and at about 30k it's time for new tires

Put them on my 2500 in September of 2016. They have about 7000 miles on them since then. So not sure how far they will go. They look almost brand new.