John's excellent Cat Scale adventure

Onyrlef · 07-10-2021, 01:25 PM

After a blowout a last week I wanted to make sure I hadn't exceeded my tires weight limits. I loaded the TM and the TV up like I had it last week and set off for the Cat Scale. Once there I weighed the TM, 3380lbs. TV, 5640lbs with TM on hitch and WDH. So I'm good. Otherwise, I then weighed the TV alone 5260lbs. Tongue weight therefore with WDH is about 380lbs (didn't have the bars on the WDH) If the WDH distributes approximately 42% of the nominal tongue weight then the weight without the WDH (nominal), should be about 650lbs. My receiver hitch (Curt) is rated at 500 lbs., 800 lbs w/ WDH.
The tires are Hartland ST 215-75-R14 "C" rated for 1870 lbs., "N" speed rating (87 mph) on a 3500 lb Dexter torsion axle.
So I'm good. Tongue weight w/ WDH is in the neighborhood of 11-12% of towed vehicle weight so that's all good too.
Btw. too. I carry a 100lb. 12' Kayak on the roof of the TM on rear driver's side and a fully loaded cargo carrier on the rear passenger side. Those were on the TM at the scale.

BaconLover · 07-10-2021, 02:27 PM

Interesting! Thanks for posting. When we first got the TM, we did all the weighing (with different combinations - no one was at the scale, so we were able to go through 3 times quickly), but I would like to try again with a full freshwater tank.

Onyrlef · 07-10-2021, 04:29 PM

The 20 gal adds 167 lbs, the 40 adds 334 lbs, water htr full adds 50 lbs. We haven't yet advanced to that primitive camping status, so we only do semi and full modern. I travel with everything drained. Besides, I'd be at or over the axle weight max with a full load of water. If I had the 5200 lb Dexter axle and 15" tires I'd be good to go though. The new 2720's are so equipped I understand.

**wbmiller3** · 07-12-2021, 06:51 AM

This reminds me that I need to re-do this weighing, since we have a new tow vehicle.

Onyrlef · 07-13-2021, 06:28 AM

Bill, I'm considering switching to a 5200 lb Dexter axle and 15" wheels, is that why you installed a lift kit?

**wbmiller3** · 07-13-2021, 07:31 PM

My 2001 TM came with the 14" wheels.

I was troubled with blowouts, even with obsessive pressure checking and a TPMS.

I put in the lift kit so I could go to 15" wheels and ST225/75R15 tires. I did not change the axle.

It has decreased, but not eliminated, tire troubles. In my latest round of tire purchases, I went with Carlisle Load Range E tires. So far I have not had a problem with the Carlisles (crosses fingers). This fall I will begin changing them out as they age out.

Onyrlef · 07-13-2021, 09:57 PM

The blowout issue is troubling me as well even though I've had just the one, but I'm not at all confident in the Hartland class C tires and even though they have an N speed rating for 87mph (not 86 and not 88????) I'm holding my speed to 65mph max. Plus I don't much care for the greater tire patch a 50 psi tire has over a 65+ psi ( the greater the patch the more heat is generated). It stands to reason that since the axle axle isn't the problem anyway, finding a 5 lug 15" wheel may work out better. Thanks

**Bill** · 07-14-2021, 08:39 AM

It is an almost-universal statement that ST (Special Trailer) tires have a speed rating of 65 mph max, and do not have a speed rating code. If you rummage around the web, you will find this statement everywhere, from almost all tire manufacturers, but subject to a lot of discussion centered on "Why 65?" You may find some good general discussion on the web site of one of the tire gurus like Roger Marble - not advertising hype.

I checked the Hartland site, and I see that they do attach a speed rating N to their ST tires. They don't discuss it, and again I have no idea why theirs should be different from all other trailer tires of the same size. The Load Index is 100, which means 1764 pounds. The max inflation is 50 psi. The Load rating is C. All same as all other ST tires in this size, including the new Goodyear Endurance tires. And I note that Hartland tires cost well less than other ST tires - not a good sign, in my uneducated opinion. On the other hand, they seem to get pretty good ratings from users.

It may be that Hartland is playing some games - hard to believe, I know. Trailer requirements (ST) are different from passenger (P) and light truck (LT) usage, and it may be that the "N" applies when the tire is mounted on a truck, rather than a trailer.

Bottom line, I think you may be too focused on that "N" rating. Goodyear Endurance 15-inch ST tires are new, made in USA, and seem to be well-received by users and dealers.

Just my opinion, of course.

Bill

**Bill** · 07-14-2021, 08:54 AM

Another thought. ST tire specs occasionally have an asterisk, and the asterisk points to some gobbldygook about how you can increase the max speed by some% if you increase the air pressure by someother% and decrease the load by yetanother%. Or something.

No one has ever been able to explain to me exactly what this means, but people continually try to use it as an excuse to drive faster, without acknowledging the part about lightening the load on the tire. Maybe that is the kind of thing Hartland is doing.

Bill

Onyrlef · 07-14-2021, 03:13 PM

Not particularly focused on the "N" rating and certainly not going to test it out, but the Hartland's were what we could get on a July 5th a holiday, after the blowout. In my uninformed opinion too, most blowouts are a perfect storm of insufficient tire pressure and too high a speed which leads to tire overheating. My particular blowout was courtesy of a deep pothole on I-20 just S. of Dallas. I've otherwise never paid much attention to the urban rumors about tires. Not sure the lawyers would let them claim an "N" rating without the data to back it up. That would be an ambulance chasers dream come true. From what I've read there are just as many bad reviews for Goodyear ST's as there are for Hartland ( Btw. too, it seemed to me most of those rave Hartland reviews sounded suspiciously fake) Meantime what I am focused on is the "c" load rating. Even at only 3400 lbs I'd be more comfortable with a "d" rated tire at 65 psi. I'm still going to hold the speed to the 65 mph max. Apparently to get to that "d" or better I'm going to have go to 5 hole 15" wheel.

John