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RoccoJohn · 08-17-2011, 07:53 AM

I have a 2009 Ford F-150 with 5.4 engine and 3.7 and max tow package. I tow a 27 FB. The tires that came with the truck are Pirelli Scorpion STR XL P275/55R20. Ford calls for 35 PSI but the tires have a max psi allowance of 44 pounds.
I notice a bit of a bulge when hooked up even though I use a Pro Pride hitch and wondered if a Light Truck tire (10 ply) instead of the 4 ply tires I have would be a better choice.
However - there doesn't seem to be a LT tire available in this size - so I would either have to go up or down in size to get a stronger tire.
Any advice?
Thanks

Sphere Guy · 08-17-2011, 08:56 AM

GaRoc, I've got the same tires on my 2010 Platinum 4x4. I know these tires are a soft compound and will not last long... I run my tires at 40 psi when towing my 2008 23 ft Safari. It's doing well and haven't seen any unusual wear. I'm looking at upgrading to a 75 ratio, minimum C rated tire. This should give me more of a comfort level and should fit inside the wheel wells. It's what I did on my old 2004 F150 4x4. and only raised my height by 1 1/2 inches.

Of course, then I have to redo all my hitch settings.

I was looking into the Michelin LTX MS2's, of course very expensive! Then having to "rebuild" the pressure sensors.

dkottum · 08-17-2011, 11:10 AM

I just received my Fall 2011 issue of "Airstream Life" where Andy Thomson writes a lengthy article "Changing Tire Sizes for Better Towing performance". Try to get your hands on this article as it addresses your question in detail.

Interesting to note he explains why a lower profile tire is a better choice for towing, and why an XL tire may be better overall than an LT tire.

doug k

Naper · 08-17-2011, 12:13 PM

Sounds like I have the same truck and trailer. I had to take the Pirelli's off. replaced with Yokohama of the same size. It made a huge difference. I think the Pirelli's are far too soft.

TinLoaf · 08-17-2011, 01:34 PM

I have an F-150 with 18 inch rims. I replaced the original 4-ply with 10-ply Load Range E tires and it was total overkill. 10-ply tires are very heavy and very stiff which really works the suspension resulting in a huge downgrade in your ride quality. I'll never do it again.

If you can find a Load Range C or an XL tire you'd have more than enough carrying capacity and you won't suffer from such an extreme degradation in ride quality.

Phrunes · 08-17-2011, 11:11 PM

Go with the BF Goodrich All Terrain TA's. D rating, great wear characteristics, relatively quiet, severe weather rated and come in your size range (aspect or cross section +/- 5%. I'd go with the 285/55R20.

slowmover · 08-18-2011, 07:39 AM

I notice a bit of a bulge when hooked up even though I use a Pro Pride hitch

There is not enough information in the OP to properly answer the question.

There is nothing wrong, per se, with a loaded tire showing a slight bulge. The real question is the weight on the rear axle. Has the combination had it's hitch rigging sorted correctly by weight scale readings? All hitches need this done, it is not optional.

Before going off to spend money on tires it would be best to use a CAT Scale to find proper weights: truck, solo, empty (except driver + full fuel); truck, solo, loaded (as if for trailer travel); trailer, empty (but for fresh water + propane + permanent supplies/equip't.); trailer, loaded, as if for travel; and tongue weights from both of those readings. (This is still the best thread on this site -- with several others as accessory -- to understand how to sort hitch rigging.)

If the hitch can be shown to be distributing the TW per FORD guidelines (probably 75% on RA and 25% on TT axles with the FA returned to un-hitched values; check FORD Towing Guide), then the load on the RA needs to be checked against both wheel and tire load ratings.

In other words, if hitching up the trailer reduces the FA reading by 260-lbs, then the hitch must be re-adjusted to distribute enough TW to bring that back.

Without numbers the rest is futile in that one may also prematurely wear a new set of tires -- even if "better" -- as some adjustments to return the FA to unhitched height/weight may be all that is needed. As confirmed by scale readings. At present there is no way to determine what tire is "better" as there is no way to determine if the present tires/wheels are performing adequately.

A TPMS is also recommended. Highly.

.

Bejasus · 08-18-2011, 11:29 AM

I have a late 2010 F-150 Lariat with 3.55 axle and 5.4 engine and 6 speed transmission. It is also fitted with the same Pirelli Scorpions. I just hauled a 22ft Safari 3575 miles and I didn't notice any issues with the performance, but my tire guy recommended I inflate the truck tires to 42 psi which I did and didn't notice any ride issues, but I also had a 10k equalizer hitch fitted prior to the trip. The Pirelli's may be a bit soft and when I come to change them, I may opt for the Goodyear Wranglers I see fitted to many of the 2011 models.

Aviator · 08-18-2011, 01:09 PM

GaRoc,

I have the same truck and tires as you from Ford. The Scorpions lasted 32,000. I just replaced them with the BFGoodrich All Terrain tires mentioned above. I purchased them through Tire Rack, and had a local shop mount them. My first towing experience will be at the month, but have been happy with them around town.

RoccoJohn · 08-18-2011, 01:43 PM

Appreciate all of the input and will head off to the scales on my next trip.
But first - a question.
If the front and rear wheel well heights are measured before and after hooking up (as recommended by the hitch literature I have seen from various manufacturers), and the measurements before and after are very close and in the same relationship as was present before hooking up, then would not the hitch setting be nearly correct? I realize that weighing is necessary to get the total weight picture, but do the wheel well heights tell the story correctly as to weight distribution after hitch hook-up?

68 TWind · 08-18-2011, 02:05 PM

I get better service out of Yokohama's than any other brand I have tried. Between all my vehicles and my kids, we have tried most brands and have never had a problem with Yokos. They stay balanced (Toyos are terrible), excellent tread life. Michelins give good service too but are way more expensive.

Aviator · 08-18-2011, 03:07 PM

Two things,

I should have typed BFGoodrich Rugged Terrain on my new tire type, and...

When I used the CAT scales, I started at even fore and aft wheel clearance, then used the scale results to mov the loaded axle weights towards even. My truck is 2X4 and I settled on 6 1/2" of rise on my propride adjustment.

I posted m results and pictures in the ProPride user thread.

Phrunes · 08-18-2011, 03:09 PM

Quote:

Originally Posted by GaRoc

Appreciate all of the input and will head off to the scales on my next trip.
But first - a question.
If the front and rear wheel well heights are measured before and after hooking up (as recommended by the hitch literature I have seen from various manufacturers), and the measurements before and after are very close and in the same relationship as was present before hooking up, then would not the hitch setting be nearly correct? I realize that weighing is necessary to get the total weight picture, but do the wheel well heights tell the story correctly as to weight distribution after hitch hook-up?

One would think. I personally would never tow with p series tires. Ford is putting these on their trucks because the truck is often the new SUV and except for weekend trips to the local hardware store many will never tow or haul to their capability. I actually use mine, towing RV, boat, dirt, concrete, I pull stumps out with it, play in the desert and the mud, deep snow in Tahoe etc. The VERY FIRST thing I ever do is buy propper LT tires and sell the takeoffs on CL. Just my two cents.

xrvr · 08-18-2011, 03:11 PM

Canadian built Firestones are good tires. jim

slowmover · 08-19-2011, 07:32 AM

Quote:

Originally Posted by GaRoc

Appreciate all of the input and will head off to the scales on my next trip.
But first - a question.
If the front and rear wheel well heights are measured before and after hooking up (as recommended by the hitch literature I have seen from various manufacturers), and the measurements before and after are very close and in the same relationship as was present before hooking up, then would not the hitch setting be nearly correct? I realize that weighing is necessary to get the total weight picture, but do the wheel well heights tell the story correctly as to weight distribution after hitch hook-up?

Measurements of height can vary depending on all sorts of small things. Move the TV or the TV/TT rig five-feet, for example, and the height will change. Hysteresis. It's a beginning, but not enough to get the hitch rigging dialed in. So, no, height measurements are not enough. It's ballpark okay, but not the same as "good".

.

dkottum · 08-19-2011, 09:52 AM

Measurements of height can vary, but so can scale weight measurements, every time you load the rig, or use water, fuel or storage tanks. Granted it won't change much, but do we need to be this exact? At least some hitch mfg's do not even mention weight scales, only measurements.

I apologize for drifting away from the op's question on tires, but would refer to my earlier post on the excellent article by Andy Thomson.

doug k

slowmover · 08-20-2011, 08:51 AM

Height is a gross measurement, the scale is a fine measurement, if you want a workable rule.

DMT · 09-04-2011, 08:36 AM

Quote:

Originally Posted by GaRoc

I have a 2009 Ford F-150 with 5.4 engine and 3.7 and max tow package. I tow a 27 FB. The tires that came with the truck are Pirelli Scorpion STR XL P275/55R20. Ford calls for 35 PSI but the tires have a max psi allowance of 44 pounds.
I notice a bit of a bulge when hooked up even though I use a Pro Pride hitch and wondered if a Light Truck tire (10 ply) instead of the 4 ply tires I have would be a better choice.
However - there doesn't seem to be a LT tire available in this size - so I would either have to go up or down in size to get a stronger tire.
Any advice?
Thanks

I have the same truck and tow a 27FB as well. Changed the Tires to Michelin LTX AT2, in size LT285/55R20. I inflate the tires to 50 psi which according to several posts on this forum seems to be the limit for stock rims.

Have you measured your axle load yet? My rear axle is always over the GAWR limit and both truck axles together are always over the GVWR, at least according to the door sticker (which lists the OEM Pirelli tires). Next time you get in your truck look at the sticker - mine states "the combined weight of cargo and occupants must not exceed 878lbs". Four adults and four sets of golf clubs would exceed that - Ford sells this as a truck?

the ponz · 10-27-2011, 05:51 PM

Quote:

Originally Posted by TinLoaf

I have an F-150 with 18 inch rims. I replaced the original 4-ply with 10-ply Load Range E tires and it was total overkill. 10-ply tires are very heavy and very stiff which really works the suspension resulting in a huge downgrade in your ride quality. I'll never do it again.

If you can find a Load Range C or an XL tire you'd have more than enough carrying capacity and you won't suffer from such an extreme degradation in ride quality.

What brand and model was the 10 ply "E" tire you had that was overkill?

TinLoaf · 10-27-2011, 05:56 PM

They were Cooper Discoverer ATR. I ran that exact tire on my old Excursion and it was a great tire. I still believe it's a great tire, but I should have gotten the load range C on the F-150.

I have about 15,000 miles on those tires and they're performing well. I like them in every way except the ride degradation.