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Old 06-09-2016, 11:12 AM   #11 (permalink)
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I think the question "what tire takes high psi the best" will only draw anecdotal responses, since such a thing to my knowledge hasn't been subject to any controlled testing.

As noted, they all- in new or very good condition- can take pressures exponentially higher than sidewall. But we don't care about that here; we are concerned with 45-55 psi pressures. I think any tire except one with a compromising issue like severely weather-checked sidewalls will give good service in that pressure range.

So by "take" do you mean ride quality or wear or something else? Ride quality certainly can suffer at 44-55 psi but there are many variables besides the tire; how soft are the springs and shocks, how heavy is the vehicle, how cushy are the seats, how rough are the local roads, what is the driver's preference, etc.

Some of my vehicles wore their tires unevenly at elevated sidewall pressures and some didn't. Could be the tire but it's also the suspension geometry, loading, how hard you corner, etc.

I know you aren't lowering but cutting the springs makes them stiffer. On a related note you haven't said what your aspect ratio preference is; while the low, low aspect ratio tires are said to theoretically have lower rolling resistance they also ride rough. Conversely the old school high aspect ratio tires by rights should give the smoothest ride what with all that sidewall available to cushion the blows even if they are run at higher than sidewall pressures. But we know there is quite a variation in tire responses between different brands and models even of the same size. Safe to say that higher load rated tires, and tires with more plies, will ride rougher.

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Aside from that, is anyone aware of a ride suspension modification that is cheaper to implement then air bag suspension?
Yes. This one is FREE!!! Start at a high, teeth-rattling pressure and lower it until you can stand it. I started at 50 psi in my F150 and it rode like it had iron locomotive wheels. Now running 42 psi which is acceptable. Also stopped by a tire store and used their wear gauge to confirm even wear. There was some evidence of higher wear in the center so I dropped psi by four to see if that helps.

I suggest you run whatever tire floats your boat and experiment with pressure to your satisfaction.

One thing I do is drive down a dusty gravel road then get out on the pavement for a few miles, then stop and see where the dust has worn away. I saw where overinflated tires still have dust on the outer treads, and lowered the psi and repeated the run until I was satisfied that the "right amount" of tread at the sides was in contact. That is how I came to use differential tire pressures, as most of my vehicles are nose-heavy I run the fronts 2-4 psi higher than the rears. Come to think of it, I'd been using the differential pressure strategy forever but in reverse as the old school VWs and Corvairs run lower pressures in the front than in the rear.

P.S. I have long had a theory that if I had the tire mounted on the widest possible rim- at the edge of the recommended range or even beyond- that it could take higher pressure before prematurely wearing the crown. Tires have been mounted this way but I don't know what their results were.

P.P.S. So basically you want to know the lowest r.r. tire. It's a hard question to answer, what with the lack of data and all. There are two more things I consider for this: OEM tires are probably better than aftermarket tires. I read about that somewhere. So what could be better than an OEM Prius tire? Also, worn tires have lower r.r. than newer tires- less rubber flexing > less hysteresis. What could be better than worn OEM Prius tires??? In fact I scored a set of worn OEM Prius tires but since my most-used vehicles are all set with decent shoes I haven't had them mounted yet.

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Old 06-09-2016, 12:34 PM   #12 (permalink)
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Originally Posted by CapriRacer View Post
Hi. Barry of Barry's Tire Tech here!


Large amounts of over-inflation pressure tends to cause rough ride, wet traction issues, center wear, groove wander, and increased puncture rates, but improved overall wear rate, fuel economy, and steering crispness. Dry traction and vibration (balance) seem unaffected. The jury is still out on whether overall durability (that is, structural failures) are affected or not as the trend seems to be there, but there aren't a lot of data points. Please note that all of the above is based on anecdotal data and self-reports over the internet. It's reliability is suspect, but it is the only data available.
I used to run a set of tires at 51 cold, and never once suffered from center wear or bad wet handling. As for trends, the only ones I have seen it for are tires inflated below some 25 psi cold, as there was a famous incident back in the 90s for firestone tires I believe. So 25 cold I assume would be like 32 hot?

Either way, its obvious some tires perform better at higher pressures then others, and hence better fuel economy, what I want to know is which LRR get the best fuel economy while not sacrificing anything else with high pressure.
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Old 06-09-2016, 12:47 PM   #13 (permalink)
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Originally Posted by Frank Lee View Post
I think the question "what tire takes high psi the best" will only draw anecdotal responses, since such a thing to my knowledge hasn't been subject to any controlled testing.
I was really hoping for somekind of controlled testing, as it is true many tires perform better and wear evenly at higher pressures of say 44 psi.


Quote:
Originally Posted by Frank Lee View Post
P.P.S. So basically you want to know the lowest r.r. tire. It's a hard question to answer, what with the lack of data and all. There are two more things I consider for this: OEM tires are probably better than aftermarket tires. I read about that somewhere. So what could be better than an OEM Prius tire? Also, worn tires have lower r.r. than newer tires- less rubber flexing > less hysteresis. What could be better than worn OEM Prius tires??? In fact I scored a set of worn OEM Prius tires but since my most-used vehicles are all set with decent shoes I haven't had them mounted yet.
Well just according to tire rack reviews, oem tires arent that great. Which isnt surprising, but continental procontacts and michelin premier a/s seem to be what people like the most, and I drive a civic hybrid.

As it stands, I think AA grade is a must for higher pressures, and so far just based off of my research, the continental purecontacts seem to be the one. The Truecontacts seem to have high user ratings, but has a temp grade of B, and only suggest 44psi max.

https://www.tirerack.com/tires/tires...lus+Technology

High ratings, but only 44 psi.

https://www.tirerack.com/tires/tires...el=TrueContact

Not as high ratings, but 51 psi.

There are others rated at 51, but these seem to take the cake in reviews.
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Old 06-09-2016, 01:22 PM   #14 (permalink)
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Well there ya go.
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Old 06-29-2016, 10:56 PM   #15 (permalink)
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The pressure rating on the side of the tire is more to do with what type of car the tire is going to go on rather than anything different with the tire construction. Different sizes of the same model tire will have different ratings.

High mileage tires will almost always be "aa-a" or "a-b" tires because of the tread compound.

My opinion? Of the 4 cars i have increased tire pressure on, i never kept them above 45 psi cold. The impact on fuel economy and treadwear is minimal above 38 psi.
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Old 06-30-2016, 04:27 AM   #16 (permalink)
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What people seem to have neglected to mention what higher tire pressures would surely increase the chance of a blowout if struck, like a kerb. In my view, just as you would have to keep a more critical eye on pressures with a low indexed tire (sidewall height), you equally have to take into account the vehicles extra load. I personally like 50 psi as i use 135/80/13s and do not carry additional weight. I haven’t done the A-B-A test, but would be surprised if this yields > 1% efficiency
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Old 06-30-2016, 10:43 AM   #17 (permalink)
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Quote:
Originally Posted by ksa8907 View Post
The pressure rating on the side of the tire is more to do with what type of car the tire is going to go on rather than anything different with the tire construction. Different sizes of the same model tire will have different ratings.

High mileage tires will almost always be "aa-a" or "a-b" tires because of the tread compound.

My opinion? Of the 4 cars i have increased tire pressure on, i never kept them above 45 psi cold. The impact on fuel economy and treadwear is minimal above 38 psi.
There are parts of this post which are right on, but there are parts that aren't.

First, the max pressure listed on the sidewall of a tire is not a rating. It is merely a statement about what the max usage pressure for that tire is. Kind of an advisory not to exceed that value.

The max pressure listed on the sidewall is not directly connected to the construction, except to say that the speed rating test requires certain pressures to be run, so the tire will reflect that and because higher speed rating require cap plies, there is a loose correlation. For example, V and higher speed rated tires are tested at 51 psi, so they will say 51 psi max, and in order to pass the test, a V speed rated tire generally needs 2 cap plies. However, there are some T rated tires with a max of 51 psi, and T speed rated tires are tested at 35 psi and don't require a cap ply to pass the test.

Tire models tend to have the same UTQG ratings and max pressures regardless of tire size, but there are some exceptions. For example, some lines of tires are original equipment lines and each tire is designed to the specs for the car it is being supplied to - and no 2 specs are the same.

High mileage tires tend not to be high temperature rating tires (that is high speed rated). You won't see many 600 and higher rated tires with AA temperature ratings.

And one last comment. If you ask the tire manufacturers for a pressure recommendation, they will point to the vehicle placard, regardless of the tire line. Put another way, what is written on the sidewall of a tire does not affect what a tire manufacturer recommends for usage pressure.

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