Clas C and tires

Funny you mention Futura Scramblers... We cared for a friend's Class C for two years while he was deployed overseas. Ran it all over Florida with zero tire problems, even though the tires were old. Plenty of other problems, coach was 25 years old, just no tire problems. Till he got back and decided to sell the coach (Class C on '83 E350). Price was good, we knew everything we'd fixed, so we bought it. First time out after we'd bought it, left rear outer tire blew! Tore out the fender molding, loosened but didn't ruin the waste tank valves.
I called around, and ended up with Pep Boys and Futura Scrambler All Season Tires. They were 8.75R16.5D, very close to the price they gave you on 16's. They went on in 2000 and we sold the RV in 2009 after only about 12000 miles. Tires looked new, had even wear, and no sidewall checking. If you can get all the DOT information, you can learn Who made those tires and (in my opinion more importantly) Where. Everybody seems to have factories everywhere, and if Michelin had a plant in China, I don't think I'd buy those Michelins.

Big trucks (18-wheelers) run Steer, Drive, and Trailer Tires. Steer is more like Highway Rib, Drive can be more like All Season, and Trailer is well, Trailer. I'd heard that RVs tend to wander on the road and running Steer tires helps keep them straight. That'd apply to the 22.5" tires. Still, I went Rib on our current coach, hoping for better tracking on the road. That said, those Scramblers never let me down, and were better in rain than our current Ribs.

Oh, I got a price for six tires and had them mounted same day. Delayed our trip, but problem resolved. I told them the price was OK but I needed them to throw in a seventh tire for spare. They did. I never rotated the rears. Rotated Spare to Left Front, Left Front to Right Front, and Right Front to Spare a few times. You don't want a tire failure then find your spare fails in 50 miles when you have 100 to go. No point in not running a new spare either. They deteriorate in storage about the same as in use.

Which is WHY you want Fresh Production Dates on your new tires!

SJ-Chris wrote:
...... As part of my "How to select tires" process, I also just stumbled upon the UTQG ratings.
https://info.kaltire.com/utqg-ratings/
Do any of you dive this deep in analyzing tires? Seems like it *could* help to compare treadwear, traction, and temperature across different brands. I haven't done it yet, but I'll have to compare the UTQG ratings of several tires to see if there is a big difference and perhaps providing a good definitive/measured reason why some more expensive tires might be worth it.

You will find that LT's do not have UTQG ratings. Only P type tires.

Any thoughts from you experts on these tires:

https://www.pepboys.com/tires/details/Futura/Scrambler%2520API/609878/00828?quantity=6
Futura Scrambler API (I was told they are made by Cooper for Pepboys).
Load rating: E
All-season tire
40,000 mile warranty
$87/tire not including installation/etc.

Part of my thinking is that I have zero chance of putting 40,000 miles on my RV over the next 5-6 years and therefore these tires will be eventually replaced because of old age rather than being worn down. Some of the other (more expensive tires) might last more miles, but that won't matter because I'll have to replace them in 5-6 years anyways.

As part of my "How to select tires" process, I also just stumbled upon the UTQG ratings.
https://info.kaltire.com/utqg-ratings/
Do any of you dive this deep in analyzing tires? Seems like it *could* help to compare treadwear, traction, and temperature across different brands. I haven't done it yet, but I'll have to compare the UTQG ratings of several tires to see if there is a big difference and perhaps providing a good definitive/measured reason why some more expensive tires might be worth it.

road-runner wrote:
...Kumho tire fiasco with Sprinter chassis motorhomes....blowouts on the original equipment Kumho tires, both on the rear . One of them took off the driver's side wheel skirt, the body panel that covers the rear wheel well...

Disappointing. Kumho isn't a famous brand, but I hadn't heard much bad about it.

Note the account of body damage at the REAR. RV bodywork is a cousin of cardboard, and it doesn't hold up well to a tread-beating.

DrewE wrote:

I tend to be of the opinion that any tire that is DOT approved is generally safe to use within its ratings, regardless of brand. I also have not made much study of the matter.

You probably aren't aware of the Kumho tire fiasco with Sprinter chassis motorhomes. I don't know what the current Sprinters ship with. In the 2017 to 2019 timeframe they came with either Continental or Kumho tires. The Continentals were ok but had a fairly high wear rate. Posts stolen from another forum describe the Kumhos better that I would:

(1)One other point about tires Make sure you do NOT have any of the Kumho tires on your unit. Not likely since all of them probably have self destructed by now But many (all?) of the Fleetwoods of that vintage came with those tires and they are not safe

(2)Late last week, we had TWO blowouts on the original equipment Kumho tires, both on the rear . One of them took off the driver's side wheel skirt, the body panel that covers the rear wheel well

(3) Don't know about source for the body panels but want to reiterate that anyone still driving on Kumhos should replace them ASAP. They are a disaster waiting to happen as you found out

The majority of the Sprinter owners with Kumho tires went with Michelin and were happy with them. Some of the Michelins were subject to a subsequent recall, but not for the blowout problem the Kumhos had. I was lucky and had Continentals for the original tires, went with Michelin when they wore out.

SJ-Chris wrote:
Tires and weights / weight ratings.......
I'd really love to see what someone else's ~31' Class C weighed when fully loaded

I've searched on various tire dealer websites (PepBoys, Firestone, Costco, Wheelworks, etc). There seem be be several LT225/75R16 E tires from known brands and other brands I'm not familiar with. Not sure which tire/brand to go with yet (lots of great discussion in this thread).

One interesting thing I found was an LT225/75R16 F rated tire (Sunfull SF-05) at Pepboys for a fairly low price. The "F" rated tire has a load rating of 121 which supports a max weight of 3197lbs (more than 500lbs more than the E rated tires).Q: Is the max PSI always stamped on rims???). Assuming that my rims were rated with enough PSI, can anyone think of a drawback of going with an F rated tire that can more easily handle the heavy load of an RV? Wouldn't it cause the tires to "work" less and therefore be less likely to have a WEIGHT CAUSED blowout?

My take on tire failure, not necessarily in order:

Underinflation from either Miscalculation or Air Loss. You already know about weight and pressure. Air Loss can be gradual like poor valves/valve installation OR use of extenders. A good set of custom valves like Borg Dually Valves will provide assurance that the air you put in your tires will stay there till you let it out or something like a puncture happens. Take my word on this. My pre-flights were miserable at the tire checking stage till I installed Borg Valves. Now it takes about a minute to confirm it's still all OK.

Abuse from curbs, potholes, running off onto the shoulder. Remember if you run off to the right, the rear outer goes off the pavement first. When it does, its load goes to the right inner. Instant shock overload.

Overloading and need I say more? I'm not sure yet that I'm sold on this "F" stuff, but going "up" doesn't increase capacity! It's still your axle, your brakes, so on and so forth.

Over-Age Tires will fail under any load condition without warning! Seven years is probably max, and that's from the date the tire was MADE not when it was mounted. I can prove that.

Poor tires just don't make sense from a financial or safety standpoint. If a tire would just blow to bits, maybe not too bad. But they shed the Tread in big pieces and that is guaranteed to destroy your fender lining, body side or trim, possibly electrical and piping. One tread whipping will cost more than several sets of tires. Get tires with a good reputation and decent availability of replacements near where you travel.

Here are axle ratings and CAT scale weights for our 31-footer, loaded with we two and all the stuff we travel with. Did several things:

Convinced me to stick with higher line tires. We run Bridgestone Duravis R250, similar to Michelin XPS RIB

Convinced me to upgrade the front axle and brakes. Notice I have 5000 there. Up through 2007 Chassis Year (before the new "nose" in 2008) that was 4600, but I did it mostly for the much bigger brakes on the 2012 axle I installed on our 2002 chassis.

Made me think twice about a 31-footer with slides. We have Zero Slides, and still came this close to max. Here are the numbers. Rated @ PSI is from Michelin's chart for 225/75R16E. I've never tried a "paste from Excel" here, so I don't know how it'll look to you.

CAT PSI Rated @ PSI
GAWR Front 5000
CAT Actual 4560 2280 65 (2335)
Axle Percent 91.2%
Pct of Total 33.0%


GAWR Rear 9450
CAT Actual 9240 4620 75 (4660)
Percentage 97.8%
Pct of Total 67.0%

GVWR Total 14450
CAT Total 13800
Percentage 95.5%

PS: I did the CAT Scale run while the front GAWR was still 4600, so we were 99% at that time. Good info to persuade the DW to support doing a fairly extensive (but very straightforward) modification out in the driveway. Drive and Braking are majorly improved.

SJ-Chris wrote:
....... Does anyone else feel like this is an uncomfortably LOW margin? .....

This is a little less than what I think is prundent, but not too bad.

SJ-Chris wrote:
....... Does anyone know, generally speaking, how the manufacturer comes up with those max axle weights? ......

Yes, they pay attention to how strong each component is and publish the weakest one. On motorized vehicles, it used to be the tires was the weakest link, but nowadays, it is usually something else.

SJ-Chris wrote:
....... Is the manufacturer adding that all in when coming up with their max load ratings? .....

He's supposed to, but usually these are chassis's made by someone else, on which a box is made and sometimes the converter doesn't do a good job.

SJ-Chris wrote:
....... Q: Is the max PSI always stamped on rims??? ......

No, unlike tires, wheels are not required to stamp weight and load limits. From what wheel engineers have told me, the bolt pattern of the wheel describes what vehicles those wheels go on, and the wheels are designed accordingly. They have also told me - in a round about way - that load is the key parameter, and inflation pressure isn't - that the wheels can withstand a lot more pressure than the max pressure of the tires that can be put on.

SJ-Chris wrote:
....... Assuming that my rims were rated with enough PSI, can anyone think of a drawback of going with an F rated tire that can more easily handle the heavy load of an RV? Wouldn't it cause the tires to "work" less and therefore be less likely to have a WEIGHT CAUSED blowout? .....

You have to use the increased inflation pressure to get that increased load carrying capacity - and that means a harsher ride.

And just a side thought: If the tire at Pep Boys is the Sunfull brand - the only Load Range F tire I saw, - never heard of them. They might be made in China, so I would proceed with caution.

Chris,
Our '15 Coachmen 28QB is about 32' bumper to bumper and rides on a 4500 Chevy chassis. Our actual weights on the unit by its self are 4400 on the front and 7800 on the back. (This is without the dolly and VW attached. Tongue weight adds about 200lbs.) We still run the original General 225/75x16 "E" tires and have no complaints with them. I set pressures based on these weights and use a TPMS to keep track of them while underway.

Gary

Tires and weights / weight ratings.......

I've got a 2006 31' Four Winds Class C and I need 6 new tires. I recently purchased the RV and notice that the tires look like (DOT) they are 5-6 years old so I'd like to just start off with a fresh set of tires to try to avoid a blowout in the near future. I am safety conscious.

My current tire size is LT225/75R16. On the specification sticker on the driver side door jam it calls for these LT225/75R16s with an 'E' rating. It lists a front axle max weight of 4600lbs, and a rear axle max weight of 9450lbs. Assuming a perfectly balanced distribution (...which is probably not a very good assumption), it means that each of the front tires should be carrying 2300lbs, and each of the 4 rear tires should be carrying 2362.5lbs if the RV is at it's "max" weight. The 'E' rating I believe is tied to (equivalent to) a load rating of 115 which specifies a max load weight of 2679lbs per tire.

Looking at my rear load (which is heavier per tire than the front), that means that there is only a ~300lb/tire margin before these tires could become overloaded. Does anyone else feel like this is an uncomfortably LOW margin? I have yet to load my RV and take it to a scale, but will do so in the future. Does anyone know, generally speaking, how the manufacturer comes up with those max axle weights? I know liquids (fresh water tank, gas tank, black/gray tanks) weigh a lot when all those tanks are full. Is the manufacturer adding that all in when coming up with their max load ratings? I assume so because otherwise they would be creating an unsafe product, but just wondering what those who have weighed their RVs have found. Can some of you who have weighed your RVs post what your axle weights were? I'd really love to see what someone else's ~31' Class C weighed when fully loaded.

I've searched on various tire dealer websites (PepBoys, Firestone, Costco, Wheelworks, etc). There seem be be several LT225/75R16 E tires from known brands and other brands I'm not familiar with. Not sure which tire/brand to go with yet (lots of great discussion in this thread).

One interesting thing I found was an LT225/75R16 F rated tire (Sunfull SF-05) at Pepboys for a fairly low price. The "F" rated tire has a load rating of 121 which supports a max weight of 3197lbs (more than 500lbs more than the E rated tires). I need to call and find out the PSI for that tire and then check the rims on my RV (Q: Is the max PSI always stamped on rims???). Assuming that my rims were rated with enough PSI, can anyone think of a drawback of going with an F rated tire that can more easily handle the heavy load of an RV? Wouldn't it cause the tires to "work" less and therefore be less likely to have a WEIGHT CAUSED blowout? Let me know your thoughts.

Thanks! This forum has been incredibly helpful for me

BFL13 wrote:
Phil, it makes sense to me that a tire at 2/3 of its max will not be under as much strain as a tire at its max holding the same weight up.

In my case with Es at 65, nowhere near their 80 max, IMO I am better off than with Ds at 65-- their max. But I am not an expert, of course.

Your comment about less strain on the tire's structure when inflated less may or may not be the case. Note that with less pressure in any given size of tire, the more it's side walls will flex and hence heat up when traveling. Heat is not good for tires.

My non-expert argument was that a higher Load Range tire will use a stronger construction method and/or use a stronger material. Which means that a higher Load Range tire will fare better no matter how you use it or how you inflate it. I think my reasoning is OK on this because after researching what tires hard core off-roaders use, I notice that their rugged tires always carry high Load Range ratings. However, off-road tires are usually large tires, so maybe higher Load Range ratings automatically follow larger tire sizes.

What I wanted for our RV was the same SIZE tires, but just higher Load Range rated tires of the same size.