OK gang,

I have decided on the Goodyear Wrangler Silent Armor, so don't tell me any other tire is better. I have a stock 265/70/17 on my 2003 Supercrew FX. Tire price is around $205/tire. I noticed that the plus zero 255/75/17 of the same tire is $128/tire. I can handle that price. I called the store and spoke with a guy there and he said there would be no noticeable difference and that tire would fit the stock rim.

Any opinions on this or has anybody done this and had any experience to impart?

Thanks.

B

 

The deminsions are as follows
265/70/17 = 31.6x10.43x17
255/75/17 = 32.06x10.03x17
The question is do you mind a narrower tire thats a little taller? Personally I dont think I would want a tire that narrow.
BTW tire rack has 255/75/17 for $108.00

 

I agree.

 

Which tire were you looking at. The 255/75R17 is a p series 44psi max rated at about 2250 lbs after derating. There are 3 different 265/70r17 tires. A p series rated at about the same as the 255 at 44, a LR C tire rated at 2470 lbs at 50 psi, and a LR E tire rated at 3195lbs at 80 psi. Which 265 tire did you price?
Also depending upon what you do, would depend upon which tire you might want to purchase. If you do a lot of heavy hauling or towing, I would get the LR C or better. They will stand up better than the P series tires. They should also handle in the turns better with heavier sidewalls. The p series may give you a little better mileage as they are lighter. 255 p is 43 lbs, 265 p is 44, 265 LR C is 48, and 265 LR E is 52. Which also says a lot about construction.

Note on P series tires take the max load carrying weight and subtract 9% for use on a light truck. You do not need to do this with LT tires as they are designed for use on a light truck.


PS, at least part of the cost difference is going to be that the 265/70R17 is probably one of the most popular sized tires. If not the most popular.

 

Most of the mileage is in the city or highway. I rarely tow anything, haul anything heavy, or go mud running.

I guess this would be question would be for guys running stock tires who use their truck for basic transportation.

B

 

I believe the stock tires are a LT tire LR C. Going to the 255 p series, you probably will notice a softer ride. Also more lean in the turns.

 

I replaced the OEM tires on my 2010 F-150 SuperCab with Goodyear Wrangler Silent Armor in 255/75/17. There is a world of difference. The SA's are much firmer (although not harsh) they have much less side/side squirm and they have much better traction on or off-road.

This was comparing both sets when they were new as the OEM tires only made about 1000 miles before I ditched them.

Highly recommended.

 

P series standard load range tires get their max load rating at 35 psi even if their maximum pressure is 44 psi. The 9 psi between 35 and 44 can be used to stiffen up the sidewall for towing and hauling or to increase fuel economy. Works very well.

 

Don't know where you get your info, but every tire and spec I see is xxxx at xx psi, whether that happens to be 35 or 44. Show me where it states this.

 

I prefer narrower tires as long as the sidewall is tall enough and built to resist tuck-under. The handling is a bit crisper, they handle deep snow better and have better directional stability on packed snow/ice and allow you to travel further on a tank of fuel on the highway. They are also better for technical off-roading in rocks and deep water and allow the fitting of a larger diameter tire without the weight becoming excessive.

 

I don't know of a handy reference on the internet but the info is good.

All P series standard load range tires achieve their maximum load rating at 35 psi, it's just how the standard works. If the maximum pressure is higher, that is just an added bonus, the tires can handle their maximum rated load at 35 psi. because that's how standard load range tires are rated.

The P series "extra load" rated tires require a higher pressure to achieve their maximum load rating (I think it's 41 psi but don't quote me on that). For maximum versatility and margin of safety I would rather have a standard load rating with a maximum pressure well above the maximum load pressure.

 

Here is the exact info from Tire Rack word for word. No where does it state about the 35. It specifically states ALL P metric and euro metric must be reduced by 9% when used on a light truck.
Other sites state basically the same thing.

 

You appear confused when you change the subject.

I was correcting your earlier mistatement that the tires under discussion had a maximum load rating at 44 psi. The actual maximum load rating on all standard load P series tires is determined at 35 psi. (even though the maximum pressure may be 44 psi). The tire's maximum load rating is not necessarily at it's maximum inflation pressure.

Here are some references I have looked up just for you:

Tire Rack:
http://www.tirerack.com/tires/tirete....jsp?techid=21
http://www.tirerack.com/tires/tiretech/tirespecskey.jsp

Pay particular attention to the quotes below:
I hope this helps clear up your misunderstanding about tire pressures.

 

Agreed, but a 44 psi P series still will not be as firm as a LR C. As shown within a make model and size, the LT tires will be manufactured to heavier, sturdier construction.

PS, it seems that is only for P series as there are LR D with a max of 50, and LR E with a max of 65. So the max would not be for a higher pressure than the tire was rated for.

 

Vertical stiffness is primarily a function of air pressure and can be calculated (or stated) as the ratio of deflection to load. A LT tire achieves it's higher load rating via higher air pressure (it deflects less under a given load but only when inflated to a higher pressure). The heavier construction is what allows it to hold more pressure. This sturdier construction that is inherent in tires with higher load ratings is not all good because an important aspect of a tires performance is it's ability to deflect. Too much OR too little deflection is undesirable.

The advice that a truck needs LT series tires is highly suspect, particularly in cases in which the primary use of the truck is unloaded. A high quality tire with a lower load rating can easily out-perform an inexpensive LT tire with a higher load rating. This is particularly true if the P series tire has adequate load margin. Here is a real world example:

Take the Goodyear Wrangler Silent Armor in 285/70/17 size. It comes in two different load ratings in this size, a P285/70/17 and a "D" load range LT285/70/17 with maximum rated loads of 2833 lbs. @35 psi and 3195 lbs. @ 65 psi respectively. As you correctly pointed out earlier, it is necessary to rate the P series tire at 2578 lbs. to make the two load ratings directly comparable (2833 lbs. x0.91=2578 lbs.).

However, the "D" load range tire is rated at 3195 lbs. only when it is inflated to 65 psi. At 35 psi the "D" load range tire is only rated to carry 2105 lbs. (compared to 2578 lbs. for the P series tire of the same size at the same 35 psi). Even inflated to 45 psi the load capacity of the "D" load range tire will be less than the P series tire at 35 psi (or even 44 psi for that matter). Why is this? It has to do with the deflection of the tire. The heavier contruction of the "D" load range tire causes it to build more heat from the same level of deflection and thus the "D" load range tire will overheat and self-destruct at pressures and loads that the P series tire can handle just fine. In otherwords, a tire with a higher load rating MUST be run at higher pressures just to survive. And that is the beauty of a P series tire that can handle more than it's maximum intended load at 35 psi but can still be inflated up to 44 psi to reduce deflection when desired and also reduce side to side squirm if necessary (for example, when towing a large trailer).

If you are looking for stronger sidewalls to resist cuts then you still want a tire in a load range appropriate for the intended loads but you will want to move to a quality all-terrain or mud-terrain tire that has sidewall cut protection built in. You do not need to buy an LT series tire to achieve this.

The old wives tale that there are no good P series tires for our trucks probably came about due to the inadequate or barely adequate P series OEM tires that manufacturers love to cut costs with. Some people who have replaced the crappy OEM P series tires with a quality LT tire will rave about the difference and then (wrongly) assume the difference was in the "P" versus the "LT" series. A cheap tire will not have adequate construction to resist side-side motion or sidewall cuts. But not all P series tires are built this flimsily. And buying a tire with too much reserve load capacity has it's own issues. So buy a tire in a load range appropriate for it's intended uses (leaving generous margins) and don't worry whether it says "LT" or "P" on the sidewall. Interestingly enough, of the two tires under discussion, the LT tire is actually $3 cheaper per tire. But that $12 in savings wouldn't cause me to buy a tire that was excessive for the intended vehicle.