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03-05-2016, 08:29 AM
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#1
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Cutty
Join Date: Feb 2016
Location: Southeast
Posts: 84
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New 10 ply tires help
My 2007 Chev suburban says to have 35lbs PSI for standard tires. I bought TOYA 10 plys for safety and the ride is not real good until it warms up the tires and they stop bouncing. But the gas mileage went out the door. Why such a change in gas mileage? The tires call for a much higher PSI that 35lbs that the dealer put in them. If I raise that up will my mileage get better and will the car computer go nuts because it is higher than it calls for.
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03-05-2016, 08:38 AM
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#2
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Senior Member
Join Date: Nov 2013
Location: Seaford, De
Posts: 2,377
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you need to run the pressure the tire says, or at least very close too it. Mileage will probably not go up, and the ride will be worse. Tires are much heavier and stiffer, but that's what's needed to handle towing safely. The tire sensors can be retrained I believe.
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David & Lynn 2014 Coachmen Chaparral Signature 327 RLKS 2016 Ford F350 Lariat CC Dually
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03-05-2016, 08:42 AM
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#3
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Senior Member
Join Date: Nov 2014
Posts: 1,179
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You went from a P metric to a LT tire? Did you change wheels too? Those wheels on your 1500 Suburban likely do not have the raring to handle much more pressure than what the tire dealer put in them.
What size did you put on vs what was on it? That likely has fooled your lie o meter which I suspect your using for your fuel economy numbers.
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03-05-2016, 08:45 AM
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#4
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Senior Member
Join Date: Nov 2013
Location: Seaford, De
Posts: 2,377
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heavier tires will effect mileage. Lots more weight to get spinning. Even if size is the same.
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David & Lynn 2014 Coachmen Chaparral Signature 327 RLKS 2016 Ford F350 Lariat CC Dually
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03-05-2016, 08:48 AM
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#5
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Moderator Emeritus
Join Date: Mar 2008
Location: St. Paul, Minnesota
Posts: 3,365
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Quote:
Originally Posted by davel1971
heavier tires will effect mileage. Lots more weight to get spinning. Even if size is the same.
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Exactly! More rotational inertia.
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2021 F350 Lariat 7.3 4X4 w 4.30s, 2018 Wildcat 29RLX
2012 BMW G650GS, Demco Premiere Slider
1969 John Deere 1020, 1940 Ford 9N, 1948 Ford 8N
Jonsered 535, Can of WD-40, Duct Tape
Red Green coffee mugs
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03-05-2016, 05:48 PM
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#6
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Senior Member
Join Date: Jan 2016
Posts: 217
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Yes. I switched my 2011 F150 to 10 ply and lost 3 litres per 100. But that are great for toeing. Much more sure footed
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03-05-2016, 05:52 PM
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#7
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Site Team
Join Date: Nov 2010
Location: Northeast Louisiana
Posts: 33,739
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Quote:
Originally Posted by bbcutright
The tires call for a much higher PSI that 35lbs that the dealer put in them.
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Am I understanding correct that you are currently running 35 psi in a 10 ply rated tire?
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2011 Flagstaff 831 RLBSS
A 72 hour hold in a psych unit is beginning to intrigue me as a potential vacation opportunity.
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03-05-2016, 06:37 PM
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#8
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Site Team
Join Date: Nov 2010
Location: Northeast Louisiana
Posts: 33,739
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This article may help explain my question above. If you can verify my question above, we can go from there:
Tire Types: Tire Load Capacities & Pressure for Euro-metric, P-metric Tires
the main jist of which is this:
'Size-for-size, compared to P-metric tires, LT tires require higher air pressures to carry equivalent loads.'
We'll need to examine your derated OE P-Metric size that you took off your truck, and see what LT size you put on, to actually find out if the above applies to your scenario.
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2011 Flagstaff 831 RLBSS
A 72 hour hold in a psych unit is beginning to intrigue me as a potential vacation opportunity.
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03-05-2016, 09:51 PM
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#9
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Cutty
Join Date: Feb 2016
Location: Southeast
Posts: 84
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Yes that's what the dealer put in them. He said to raise the pressure when pulling a TT. Didn't make sense to me......
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03-05-2016, 09:57 PM
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#10
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Site Team
Join Date: Nov 2010
Location: Northeast Louisiana
Posts: 33,739
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Quote:
Originally Posted by bbcutright
Yes that's what the dealer put in them. He said to raise the pressure when pulling a TT. Didn't make sense to me......
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OK, we need to look into this further. If your truck is handy, can you open the driver side door, and look on the jamb (but it can be on the door itself). There should be a tag there that states the OE tire size and air pressure (front and rear). Can you note this along with the weights on the tag, and then also note the 10 ply tire you purchased, and the size of it.
I can get you the correct info from all of that.
Thanks.
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2011 Flagstaff 831 RLBSS
A 72 hour hold in a psych unit is beginning to intrigue me as a potential vacation opportunity.
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03-05-2016, 11:33 PM
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#11
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Senior Member
Join Date: Jul 2012
Location: SE Arizona's Gila Vally
Posts: 1,507
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Okay here we go again. Forget the door sticker when changing from P metric tires to LT tires. Because this is a modification using this as a reference for air pressure is no longer applicable.
Check the sidewall on the tire for the max correct air pressure for the tire you are now installing or have installed. Lets say most 10 ply tires call for 85psi max. This is the pressure to set the tire when fully loaded or towing. Airing down to 65psi is about the lowest you want to go with a 10 ply tire when not loaded or towing. Bigger heavier tire will affect fuel mileage and ride when empty but really make a difference when loaded.
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2016 RAM 1500 - 2016 Keystone Laredo 265SRK
The road goes on forever and the party never ends.
Illegitimum non carborundum
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03-06-2016, 01:12 AM
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#12
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Senior Member
Join Date: Nov 2015
Location: Rancho Santa Margarita, CA
Posts: 347
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I have a 2014 Suburban and I went from P rated to LT rated 10ply. The tire dealer had to reset the air pressure defaults to handle the higher pressure required for the LT tires. I run them at 65 cold. When towing, they go up to almost max rating of 80. When not, they stay under 70. I did not notice a mile/gal decrease.
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03-06-2016, 06:56 AM
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#13
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Senior Member
Join Date: Sep 2015
Posts: 1,022
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What size tires were on the truck, and what size tires went on?
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David and Vicki
19-month-old English Springer Spaniel "Sadie"
2019 Silverado LTZ Duramax
2023 GDRV Reflection 150 226RK
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03-06-2016, 08:03 AM
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#14
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Senior Member
Join Date: Mar 2015
Posts: 303
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"3 liter per 100" doesn't help me much...
I'm considering this change myself in a month or two. Can anyone describe in MPG what sort of loss I might expect? I currently get 17.5mpg on my daily work commute.
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2013 F150, EBoost,4x4,CC, MaxTow
2015 Surveyor 245BHS
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03-06-2016, 09:45 AM
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#15
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Cutty
Join Date: Feb 2016
Location: Southeast
Posts: 84
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The tires are LT275/65R18 Toya's 550KPG 80PSI Cold
The yellow sticker says P265/65R18 S cold pressure says 220kPa, 32PSI Front and Rear
Spare P265/70R17 S 240 KPa, 35 PSI.
Not sure why I have a 17 inch spare? that's crazy.
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03-06-2016, 09:50 AM
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#16
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Senior Member
Join Date: Nov 2014
Posts: 1,179
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To be of any use to you the tires need to carry 80PSI. But sadly your wheels probably cannot handle that pressure. Lets face it,you got the wrong tires for your SUV. Dealer should never have sold them or installed them on your vehicle.
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03-06-2016, 09:50 AM
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#17
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Cutty
Join Date: Feb 2016
Location: Southeast
Posts: 84
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I lost almost 3 miles per gallon but maybe due to tires being under inflated though. Going to raise pressure to see if it helps and will let you know if it effects the ride and mileage. Going LT was expensive almost twice the cost of conventional.
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03-06-2016, 09:53 AM
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#18
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Site Team
Join Date: Nov 2010
Location: Northeast Louisiana
Posts: 33,739
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Thanks bbcutright, I'll plug in the numbers and post a lot of additional information that may be of help to your situation. It may take me awhile to get it all typed up.
Did it have your OE weights on that tag too, that would save some time?
I'm wanting to see if it's around the 2135 lb mark per tire.
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2011 Flagstaff 831 RLBSS
A 72 hour hold in a psych unit is beginning to intrigue me as a potential vacation opportunity.
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03-06-2016, 09:54 AM
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#19
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Cutty
Join Date: Feb 2016
Location: Southeast
Posts: 84
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Are you saying I need new rims also? Or just regular tires on these old rims. Am I at risk for tire failure running at 80 because of the rims?
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03-06-2016, 09:56 AM
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#20
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Senior Member
Join Date: Sep 2015
Posts: 1,022
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Quote:
Originally Posted by bbcutright
The tires are LT275/65R18 Toya's 550KPG 80PSI Cold
The yellow sticker says P265/65R18 S cold pressure says 220kPa, 32PSI Front and Rear
Spare P265/70R17 S 240 KPa, 35 PSI.
Not sure why I have a 17 inch spare? that's crazy.
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You went up a size with the new tires. They are a larger diameter. Your speedo is off. And, you've lowered the effective rear end gear ratio as well. The engine's going to work harder to pull your TT.
I roll on 20's and have an 18" spare - on a steel wheel. I'll bet you have aluminum wheels and a steel spare wheel too. It's cheaper to equip them that way.
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David and Vicki
19-month-old English Springer Spaniel "Sadie"
2019 Silverado LTZ Duramax
2023 GDRV Reflection 150 226RK
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