Amazed at tire pressures affect on MPG
#16
08-16-2015, 07:57 AM
While I enjoy your 24 pages specific information, it doesn't address the issue of the conversation.
We are talking about fuel economy changes relating to tire pressures.
Your (somewhat unfriendly-worded) retort is in regards to maximum weight capabilities. If you have another 24 pages related to rolling resistance or fuel economy we'd love to see it.
We are talking about fuel economy changes relating to tire pressures.
Your (somewhat unfriendly-worded) retort is in regards to maximum weight capabilities. If you have another 24 pages related to rolling resistance or fuel economy we'd love to see it.
#17
08-16-2015, 10:03 AM
#18
08-16-2015, 02:58 PM
Maybe. At 80psi the ride is fine on most the roads around here. Not too many pot holes and patched roads. The ride is a little more jarring on rough roads at 80psi, but luckily even the country roads are not rough around here. Just pretty bouncy.
I feel pretty comfortable at 80psi. If I have a long highway trip I may try 90psi to see if there is a difference. Who knows, more may be better. my track car loves higher than recommended tire pressure. Although the track usually doesn't have any pot holes.
I feel pretty comfortable at 80psi. If I have a long highway trip I may try 90psi to see if there is a difference. Who knows, more may be better. my track car loves higher than recommended tire pressure. Although the track usually doesn't have any pot holes.
Yeah.....
#20
08-16-2015, 04:39 PM
There is no reason to guess, this IS an exact science.
For the factory LT225/75R16 that comes on an E-350 the tires are rated at 1,940 lbs each @ 50 PSI. At 65 PSI they are rated at 2,335 lbs each, and 2,680 at the max of 80 PSI.
I've never weighed an empty van, but the max front GAWR is 4,850 lbs for an E350. So a loaded diesel van should never be over that, so nothing over 70 PSI should ever be needed.
The extra 15 PSI adds 690 lbs of payload capacity. Do you think you're getting close to 5,360 lbs on that axle?
For the factory LT225/75R16 that comes on an E-350 the tires are rated at 1,940 lbs each @ 50 PSI. At 65 PSI they are rated at 2,335 lbs each, and 2,680 at the max of 80 PSI.
I've never weighed an empty van, but the max front GAWR is 4,850 lbs for an E350. So a loaded diesel van should never be over that, so nothing over 70 PSI should ever be needed.
The extra 15 PSI adds 690 lbs of payload capacity. Do you think you're getting close to 5,360 lbs on that axle?
Some of the different tire wear i experience may also have to do with the lack of alignment adjust-ability on the van. There is total toe adjust-ability, but not much else. Camber can be adjusted by bending the I-Beam, although the machines to do this are not normal equipment at an alignment shop now a days. I can say that through the 3 sets of tires I have gone through I get uneven tire wear at the 65psi. The edges wear much more than the middle. This does not happen at 90psi and it doesn't increase center wear to match the edge, it reduces edge to match the middle.
As far as how much affect tire pressure has on mileage, we would want to look at how the rolling resistance changes on a specific tire as pressure changes at a constant load weight. Rolling resistance does definitely affect MPG as can be seen by different tread patterns.
#21
08-16-2015, 04:46 PM
I will have to read thought the LT portion of the info provided to see the details. At a glance it looks at load rating as is relates to tire pressure. I wonder what guidelines were used to determine the safe load at the pressure? I would be interested to see if there is information about the change in the size/shape of the contact patch at different loads and pressures etc. Also does PSI for Safe Load Rating=Optimal PSI for a certain load.
Some of the different tire wear i experience may also have to do with the lack of alignment adjust-ability on the van. There is total tow adjust-ability, but not much else. Camber can be adjusted by bending the I-Beam, although the machines to do this are not normal equipment at an alignment shop now a days.
As far as how much affect tire pressure has on mileage, we would want to look at how the rolling resistance changes on a specific tire as pressure changes at a constant load weight.
Some of the different tire wear i experience may also have to do with the lack of alignment adjust-ability on the van. There is total tow adjust-ability, but not much else. Camber can be adjusted by bending the I-Beam, although the machines to do this are not normal equipment at an alignment shop now a days.
As far as how much affect tire pressure has on mileage, we would want to look at how the rolling resistance changes on a specific tire as pressure changes at a constant load weight.
Regarding alignment though; there are shims for adjusting camber and caster. They are sold one at a time, for a certain desired change.
http://www.rockauto.com/info/729/729...55_1__ra_p.jpg
The center hole is offset a certain amount that moves the position of the upper ball joint in/out, and for caster forward/backward.
#22
08-19-2015, 03:40 AM
You'd have better luck playing pickup sticks with your butt cheeks, IMHO.
#23
08-19-2015, 04:59 AM
Tires would wear in the middle from over inflation decades ago. Not now.
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