Should I buy a "B" Temperature tire for 2016 Pilot?

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2,147
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Chicago, IL
Originally Posted by Cressida
Originally Posted by CapriRacer
The difference in max inflation pressure? T rated tires are speed tested at 35 psi, and H rated tires are tested at 44 psi, so it appears the max pressures are following. (A side note: There are some vehicles that call for unusually high inflation pressures and I wonder if those max pressures are reflecting that!)
Many vehicle manufacturers list on their tire placard a recommendation of 10 to 12 lbs. lower than that 44 psi that you say the H rated tires are speed tested. If one runs an "H" rated with the vehicle recommended (e.g. 32 psi); does that mean there is an additional margin of safety, or can you help us learn what that difference might mean to the tire behavior or characteristics (if anything) ?
Interesting question - complicated answer. The set up: For every tire, there is a load table where the relationship between load carrying capacity and inflation pressure is defined. There is also the max load and its corresponding pressure indicated. For Standard Load Passenger Car tires, the max load occurs at 35 psi (2.5 bar, 250 kPa for metric tires = 36.3 psi) regardless of the speed rating. (For reference: metric tires = those tires not following the American tire standards which are expressed in English units, but are essentially the same) Where the additional margin of safety comes in is that the H rated tire has more speed capability than the S or T rated tires even at those lower pressures. For practical purposes, higher speed rated tires can be made to perform EXACTLY like lower speed rated tires, because the things that control wear, traction, ride, and handling are independent of what controls speed capability - BUT - it is common for higher speed rated tires to be designed to handle better (and therefore ride worse), get better traction (but wear worse, and get worse fuel economy). The only thing that is always worse for higher speed rated tires (all other things being equal) is fuel economy - and that is only slightly worse - not enough to worry about! Other types of tires, such as XL, LT, ST, etc. behave similarly, but the details vary.


Interesting, I would have assumed that the lower temperature rating would imply worse fuel economy. My logic being that the additional heat build up is proportional to rolling resistance as the materials flexed. Can you share, maybe in just general terms, what the mechanics are behind the decrease in fuel economy? Is it just the additional weight penalty for the stiffer construction?

Thanks for sharing your tire knowledge!!
 
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3,954
Location
Somewhere in the US
Interesting, I would have assumed that the lower temperature rating would imply worse fuel economy. My logic being that the additional heat build up is proportional to rolling resistance as the materials flexed. Can you share, maybe in just general terms, what the mechanics are behind the decrease in fuel economy? Is it just the additional weight penalty for the stiffer construction?

Thanks for sharing your tire knowledge!!
First, the Temperature Rating is a misnomer. It has nothing to do with temperature and everything to do with speed capability! I don't understand why they named it that.

So a lower Temperature Rating does NOT mean the tire runs hotter, and a higher Temperature Rating does NOT mean the tire is more resistant to heat.

But you are right that heat generation = rolling resistance. What controls rolling resistance is the amount of deflection (mostly inflation pressure!), the amount of tread rubber, and the properties of the tread rubber (called hysteresis.) Notice anything involved in speed capability is absent! (except I neglected the affect the cap plies play in adding mass to the tire, but that is pretty small!)

Speed capability is mostly caused by restricting tire growth due to centrifugal forces - which basically means cap plies. But cap plies don't play much of a role in deflection (which ties to rolling resistance.)

Now, you may say that tire stiffness must play a role here - and you are right except the biggest contributor to tire stiffness is inflation pressure. The tire's natural casing stiffness is a small fraction of the total stiffness, so it hardly plays a role in rolling resistance.
 
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230
Location
NorCal. USA
Thank you, CapriRacer, for all your tire insight! No one has mentioned “S” speed rated tires, which are only a few mph under “T” rating.

We have a 2008 Buick Enclave, which had Goodyear Forteras as OEM tires. They are S speed rated, so naturally I wanted a “better” tire. A friend owned a Cooper tire shop, so I was strictly using Coopers. I think the first set we put on were CS4, probably H rated, they were incredibly noisy, granted I may have neglected a rotation. The CS5 turned out to be better, but even with religious rotations, they became noisy and vibrating even tho balanced and aligned.

My friend closed the tire shop, so now I’m contemplating going back to the OEM S rated Forteras. My wife loved the ride when the car was new, never been the same since we started using Coopers. To be fair, the Coopers were always H speed rated, and A Traction & Temp, which I’m now seeing is misleading. The Fortera is A Traction and B Temp, which should be good because we will never run 115 MPH.

Any comments on the advantage/disadvantage of an S speed rating?

Thanks!!
 
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10,914
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MA
I always prefered the lower speed rating. You normally get better gas mileage and the tire lasts longer. But you give up a few things like traction. I had Goodyear tripletreds on my Taurus at one point. The T rated tires were good for 80k and the H rated tires just had a 70k warranty. I think I actually got 80k out of the rear tires and they still had 4/32's worth of tread on them. Didn't really rotate them, the fronts might have worn out by 50k.
 
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Somewhere in the US
Any comments on the advantage/disadvantage of an S speed rating?

S and T speed rated tires can fail from tread separation, where H and higher are practically immune. I think that is enough to warrant using at least an H rated tire where ever possible.

Now, you may hear folks say that higher speed rated tires wear worse, get worse fuel economy, ride worse, etc., but that's only sort of true, and it isn't the speed rating that causes this.

Ya' see, high performance cars have tires that grip better, are more responsive to steering input, and capable of higher speeds. All that comes as a package for the vehicle and it isn't the speed rating that is driving it. You will find many tires with higher speed ratings that wear well, and are softer riding. Fuel economy is a whole different kettle of fish.
 
Messages
230
Location
NorCal. USA
S and T speed rated tires can fail from tread separation, where H and higher are practically immune. I think that is enough to warrant using at least an H rated tire where ever possible.

Now, you may hear folks say that higher speed rated tires wear worse, get worse fuel economy, ride worse, etc., but that's only sort of true, and it isn't the speed rating that causes this.

Ya' see, high performance cars have tires that grip better, are more responsive to steering input, and capable of higher speeds. All that comes as a package for the vehicle and it isn't the speed rating that is driving it. You will find many tires with higher speed ratings that wear well, and are softer riding. Fuel economy is a whole different kettle of fish.
Thank you, CapriRacer, so how would I know which H rated tires are going to ride better? The Buick came with these tires as OEM and they have an S rating, and they rode well.
 
Messages
230
Location
NorCal. USA
I always prefered the lower speed rating. You normally get better gas mileage and the tire lasts longer. But you give up a few things like traction. I had Goodyear tripletreds on my Taurus at one point. The T rated tires were good for 80k and the H rated tires just had a 70k warranty. I think I actually got 80k out of the rear tires and they still had 4/32's worth of tread on them. Didn't really rotate them, the fronts might have worn out by 50k.
Thanks, Wolf, I actually prefer better traction, short wearing tires over trying to squeeze more life out of tires that may already be weather checking.
 
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4,252
Location
Central Maryland
It is a very competitive marketplace, there are plenty of tires to choose from, I don't limit myself to one brand... unless I have some oddball size (I don't) I see NO reason to buy inferior tires. Since I'm no longer a poor college student, I'm done with A/B tires. I can afford it, there are plenty to choose from, nothing but A heat rating for me.
 
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