Some Load Range E Tires are 65 PSI Max?? - Ford Powerstroke Diesel Forum
Wheels, Tires, and Brakes Here's where you can post all your topics and questions about wheels, tires and brakes.
Sponsored by Discount Tire

Powerstroke.org is the premier Diesel Truck Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 07-04-2012, 08:18 AM
Premium Member
 

Join Date: Aug 2009
Location: Somewhere Between Good and Bad
Posts: 1,501
Thanks: 4
Thanked 22 Times in 22 Posts
Feedback Score: 0 reviews
Some Load Range E Tires are 65 PSI Max??

School me on this.

I always thought that Load Range E tires (commonly referred to as "10 plys") had a max PSI of 80, and that Load Range D tires (referred to as "8 plys") had a max PSI of 65. It turns out that most often this is the case - but not always.

In looking at some of the larger Toyo MT tires (315/60/r20), they list this tire as a 10 ply, Load Range E, with a max PSI of only 65. It has a Load Index of 125 which equates to approximately 3,500 LBS of capacity per tire.

The next size smaller Toyo MT tire (275/65/r20) is also a Load Range E, 10 ply, but has a max PSI of 80. Tire has a Load Index of 126 which equates to approximately 3,700 LBs of capacity per tire.

Both tires are E rated, 10 ply, and have 3 ply sidewalls. So, the THEORETICAL question is, if loaded with ~3,000 LBS on each tire, would they feel the same going down the road? A stiff sidewall tire is important with truck campers and other high profile loads with tendencies to sway.
Would the larger tire with a lower max PSI feel more mushy? Asking because I carry a Truck Camper periodically and go off road with it, and I'm considering going to this tire size the next time I need tires.

Thanks-
JS
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 07-04-2012, 08:36 AM
Compression Ignition Addict
 

Join Date: Feb 2008
Posts: 8,272
Thanks: 69
Thanked 196 Times in 187 Posts
Feedback Score: 0 reviews
not sure what your going to be better with but I did notice the variable in psi for some tires

I run the Toyo D rated tire at 50 psi .. I inflate using the chalk test myself

when I had E's rated at 80 psi I had them under 70 unless towing heavy

Quote:
Tire and Rim Association. As an example, their 2010 Year Book shows that Load Range C tires may require 35 psi (240 kPa) or 55 psi (380 kPa), Load Range D tires may require 50 psi (340 kPa) or 65 psi (450 kPa), and Load Range E tires may require 65 psi (450 kPa) or 80 psi (550 kPa) to achieve their Load Index and Maximum Loads.[9] This is also the case in the tables published by major tire makers, who do follow these TRA standards and have multiple inflation pressures for the same Load Range in the tires they sell. [10]

It is essential to consult the guides like those just mentioned when making tire substitutions, and to read exactly what is imprinted on the sidewalls of tires. A different size of tire with the same Load Range may require a higher inflation pressure, and may fail in use if under-inflated.
Reply With Quote Quick reply to this message
  #3  
Old 07-04-2012, 08:36 AM
Compression Ignition Addict
 

Join Date: Jul 2007
Posts: 5,470
Thanks: 2
Thanked 10 Times in 10 Posts
Feedback Score: 0 reviews
I am not a fan of the lower PSI e rated tires. I have had a set in the past, and they felt mushy. The tire shop put them on by mistake, and I made them replace that set with the tires i originally specified. The truck didnt feel right with the low psi tires. The tire shop told me there was no difference, and offered me some money back, but I wanted the tires I specified. They did it, but were mad because they had to eat a set of tires and the cost of M&B'ing them.
Reply With Quote Quick reply to this message
  #4  
Old 07-04-2012, 08:45 AM
Compression Ignition Addict
 

Join Date: Sep 2010
Location: Delaware
Posts: 797
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
My truck is much better with cross winds with my BFG's which are a "true" E rated tire with a 3860lb/ea load capacity compared to the stock E rated Good Years.

When towing my car i run 70psi cold f/r and it drives and tracks much better than the goodyears did on the same trip. No more wiggle from the front end and no longer feel cross winds enough to need actual wheel correction.

Jason
Reply With Quote Quick reply to this message
  #5  
Old 07-04-2012, 11:41 AM
Premium Member
 

Join Date: Aug 2009
Location: Somewhere Between Good and Bad
Posts: 1,501
Thanks: 4
Thanked 22 Times in 22 Posts
Feedback Score: 0 reviews
Good info guys. Many thanks. Almost seems like a 65 psi E rated tire really performs like a D rated tire.
Reply With Quote Quick reply to this message
  #6  
Old 07-04-2012, 12:25 PM
Compression Ignition Addict
 

Join Date: Feb 2008
Posts: 8,272
Thanks: 69
Thanked 196 Times in 187 Posts
Feedback Score: 0 reviews
when I went to a larger D rated it had a higher load rating than my E rated and actually rode better // also no sway but that can be tire brand dependent
Reply With Quote Quick reply to this message
  #7  
Old 07-05-2012, 03:03 PM
Powerstroke.org Rookie
 

Join Date: Mar 2011
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
It has to do with the width of the tires. LT Tires that are wider than 295mm (11.50") will have a reduced max inflation pressure.

So, even though both sets of tires were load range 'E', the tire with the '315' section width has a lower max inflation pressure of 65psi, as opposed to the '275' section width tire with 80 psi.

To answer your question about how the tires will feel (I also have a truck camper and have run a similar set of tires), I can tell you that the 65psi tires will indeed feel more 'mushy' than the 80psi tires. In this particular case, you also have less sidewall in the 80psi tires, which means less rubber to flex.
Reply With Quote Quick reply to this message
  #8  
Old 07-25-2012, 05:08 AM
Member
 

Join Date: Apr 2009
Location: Victor Harbor South Australia
Posts: 40
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
LT Tires and How They Work

Quote:
Originally Posted by Brian_A View Post
It has to do with the width of the tires. LT Tires that are wider than 295mm (11.50") will have a reduced max inflation pressure.

So, even though both sets of tires were load range 'E', the tire with the '315' section width has a lower max inflation pressure of 65psi, as opposed to the '275' section width tire with 80 psi.

To answer your question about how the tires will feel (I also have a truck camper and have run a similar set of tires), I can tell you that the 65psi tires will indeed feel more 'mushy' than the 80psi tires. In this particular case, you also have less sidewall in the 80psi tires, which means less rubber to flex.
G'day Brian,

You are pretty well on track with what you said.

I got the info below and kept it as reference material. I cannot recall where I got it, but it was an article by one some tyre company boffin (Matt) on this very subject skanj0 started the thread on.

It's a bit long winded but is well explained.

LT Tires and How They Work
Ever wonder when reading tire reviews with complaints about "squishy" or "slow responding" traits.... Is the tire to blame or was it the size the user decided to run? Did this driver upgrade from a stock tire with an 80psi max pressure to a larger tire with a 65psi max?

These questions pop into my mind time and time again and the answer is not always in the review.

With LT-Metric Sizing and LT-Flotation Sizing being the most popular LT Sizing you'll find on today's trucks, and by today's trucks we mean SRW 1 ton, 1/2 ton and 3/4 ton, we decided to take some time to explain the LT Tire System and focus on load carrying capacity. In this write-up we will define LOAD RANGE and LOAD INDEX and explain in detail how the two work in conjunction with each other to determine load carrying capacity. This topic can be some what confusing so bear with us to the end and if you have any questions please feel free to post them here.

Below is an example of LT-Metric Sizing and LT-Flotation Sizing. We've broken down the characters and numbers in each size to explain what they mean, which most of you already know.

LT-Metric SizingLT265/75R16/E 123R
LT = Light Truck Designation
265 = Section Width (mm)
75 = Aspect Ratio
R = Radial Construction (most common construction used today)
16 = Rim Diameter (inches)
E = Load Range
123 = Load Index
R (after load index) = Speed Rating

LT-Flotation Sizing31x10.50R15LT/C 109S
31 = Tire Diameter (inches)
10.50 = Section Width (inches)
R = Radial Construction (most common construction used today)
15 = Rim Diameter (inches)
LT = Light Truck Designation
C = Load Range
109 = Load Index
S = Speed Rating

Like mentioned above, we want to specifically look at the Load Index and Load Range. Without the Load Range and Load Index, you cannot determine the maximum load carrying capacity of the tire.

Q: What is LOAD RANGE?
A: LOAD RANGE (also known as the load range description) is the load range rating found on the sidewall of LT tires. It's used to determine the maximum load carrying capacity of the tire UNDER A DEFINED MAXIMUM INFLATION PRESSURE.

Q: What is LOAD INDEX?
A: LOAD INDEX is an assigned number ranging from 0 to 279 that corresponds to the LOAD-CARRYING CAPACITY of a tire.

Like most of you know, Load Range describes the ply rating of the tire.
It's important to remember that these are ONLY RATINGS and not the actual number of ply's like it used to be back when tires were made of cotton belts (bias). Below are the most common Load Ranges you'll see on today's trucks.
C = 6 ply rated D = 8 ply rated E = 10 ply rated

Now here's where it can get a bit confusing.
It's commonly assumed that C rated tires hold a maximum pressure of 50 PSI, that D rated tires hold a maximum pressure of 65 PSI, and E rated tires hold a maximum pressure of 80 PSI. This information is correct but only applies to a certain tire size range, or rather, section width.
Here's what you need to focus on.

LT tires that are 295mm (LT-Metric) in section width or 11.50" in section width (LT-Flotation) and narrower, will carry the commonly associated maximum pressure.
C = 6 ply rated and hold a maximum pressure of 50 PSI
D = 8 ply rated and hold a maximum pressure of 65 PSI
E = 10 ply rated and hold a maximum pressure of 80 PSI
Not so tricky I hope. So you're probably thinking to yourselves, what about the other sizes? And I'll tell you...

LT tires that are 305mm (LT-Metric) in section width or 12.50" (LT-Flotation) and wider, still carry the same ply rating/Load Range but hold a different maximum inflation pressure. The maximum inflation pressure on these wider sizes lose 15 PSI from the maximum inflation pressures above.

The new inflation pressures on these wider sizes are as follows:
C = 6 ply rated and hold a maximum pressure of 35 PSI
D = 8 ply rated and hold a maximum pressure of 50 PSI
E = 10 ply rated and hold a maximum pressure of 65 PSI

Now what about Load Index?
Like mentioned previously, Load Index is an assigned number that corresponds to the load carrying capacity. More specifically, at the maximum pressure. The assigned number or Load Index can be seen on the chart below.
*Please note that this chart only goes up to 150 as most LT truck tires today do not exceed 128.

So lets take the Load Index 123 for example.
This Load Index tells us that the corresponding load carrying capacity is 3417lbs at maximum pressure. Now it doesn't show what the maximum pressure is so we now have to go look at the Load Range on the tire we are looking at.

Taking the example of LT-Metric Sizing listed earlier (LT265/75R16/E 123R). We know the tire is 10 ply rated and is narrower than 295mm in section width which tells us that the maximum inflation pressure is 80 PSI.
By using the Load Index chart we know the 123 Load Index carries 3417lbs at maximum pressure. So from what we have discussed, we now know that the LT265/75R16/E 123R tire carries a maximum load of 3417lbs. @ 80 PSI.
Now taking the example of LT-Flotation Sizing listed earlier (31x10.50R15LT/C 109S), we know the tire is 6 ply rated and is narrower than 11.50" in section width which tells us that the maximum inflation pressure is 50 PSI.

By using the Load Index chart we know the 109 Load Index carries 2271lbs at maximum pressure. With this information we now know the 31x10.50R15LT/C 109S tire carries a maximum load of 2271lbs @ 50 PSI.

Here's where it get's fun.

A lot of people think that Load Range E tires will always carry more weight than the lower ply rated/Load Range tires. This is not always the case. Let me show you an example.

A common OE (original equipment) LT tire size is LT245/70R17/E 119S. By using what we have learned above we know that this LT tire size carries 2998lbs @ 80 PSI. Now lets look at an LT315/70R17/D 121T which is a common plus size LT tire. Again, from what we have learned above we know this tire carries 3197lbs @ 50 PSI.
So even though the OE tire we used for an example is E rated with a maximum pressure of 80 PSI, the plus size D rated tire carries more weight at a lower pressure. In other words, LOAD RANGE E doesn't always mean the tire can carry more weight at maximum pressure when compared to LOAD RANGE D at maximum pressure.

Here's where your application and uses come in.

What does this mean to you if you are upgrading from the stock E Load Rated tire with an 80psi max to a new, larger, E rated tire with a 65psi max What if your upgrading to a larger size that is D load rated?

If you do not tow much it may not matter as long as your new tire carries equal to, if not a higher, load index number.
The new tire will still be able to carry at least the same weight at 65psi as your stock tire would at 80psi.
The only real difference is the way the vehicle may handle under load. If you are accustomed to towing with 80 psi in your tires and now you are only able to tow with 65psi, your vehicles response can feel squishy or lazy and you can experience a bit more "roll" as the vehicles weight shifts in turns.

How do you tell if the E Load Rated tire you are looking to buy has a 65psi or 80psi max?
On our website we indicate all 80psi E Load Rated tires as "E1" and all 65psi E Load Rated tires as "E2" in the tire size. Same thing goes for "D" and "C" Load Rated tires.

I hope this information helps.
-Matt
__________________

Cheers,
Reg
Reply With Quote Quick reply to this message
  #9  
Old 07-25-2012, 07:43 AM
Compression Ignition Addict
 

Join Date: Feb 2011
Location: Rochester
Posts: 197
Thanks: 1
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Im running a D load 65psi max tire. The door tag calls for 55psi front/50psi rear on my early 99. When towing, i put the tires up to 60 in the rear cold and they do just fine. I guess you could call them a little "mushy" but I dont notice much of a difference than the bfg a/ts i took off. Its all personal preference really.
Reply With Quote Quick reply to this message
  #10  
Old 07-25-2012, 08:26 AM
Powerstroke.org Sponsor
 

Join Date: Apr 2008
Posts: 820
Thanks: 9
Thanked 10 Times in 7 Posts
Feedback Score: 0 reviews
Quote:
Originally Posted by Reg Bichel View Post
G'day Brian,

You are pretty well on track with what you said.

I got the info below and kept it as reference material. I cannot recall where I got it, but it was an article by one some tyre company boffin (Matt) on this very subject skanj0 started the thread on.

It's a bit long winded but is well explained.

LT Tires and How They Work
Ever wonder when reading tire reviews with complaints about "squishy" or "slow responding" traits.... Is the tire to blame or was it the size the user decided to run? Did this driver upgrade from a stock tire with an 80psi max pressure to a larger tire with a 65psi max?

These questions pop into my mind time and time again and the answer is not always in the review.

With LT-Metric Sizing and LT-Flotation Sizing being the most popular LT Sizing you'll find on today's trucks, and by today's trucks we mean SRW 1 ton, 1/2 ton and 3/4 ton, we decided to take some time to explain the LT Tire System and focus on load carrying capacity. In this write-up we will define LOAD RANGE and LOAD INDEX and explain in detail how the two work in conjunction with each other to determine load carrying capacity. This topic can be some what confusing so bear with us to the end and if you have any questions please feel free to post them here.

Below is an example of LT-Metric Sizing and LT-Flotation Sizing. We've broken down the characters and numbers in each size to explain what they mean, which most of you already know.

LT-Metric SizingLT265/75R16/E 123R
LT = Light Truck Designation
265 = Section Width (mm)
75 = Aspect Ratio
R = Radial Construction (most common construction used today)
16 = Rim Diameter (inches)
E = Load Range
123 = Load Index
R (after load index) = Speed Rating

LT-Flotation Sizing31x10.50R15LT/C 109S
31 = Tire Diameter (inches)
10.50 = Section Width (inches)
R = Radial Construction (most common construction used today)
15 = Rim Diameter (inches)
LT = Light Truck Designation
C = Load Range
109 = Load Index
S = Speed Rating

Like mentioned above, we want to specifically look at the Load Index and Load Range. Without the Load Range and Load Index, you cannot determine the maximum load carrying capacity of the tire.

Q: What is LOAD RANGE?
A: LOAD RANGE (also known as the load range description) is the load range rating found on the sidewall of LT tires. It's used to determine the maximum load carrying capacity of the tire UNDER A DEFINED MAXIMUM INFLATION PRESSURE.

Q: What is LOAD INDEX?
A: LOAD INDEX is an assigned number ranging from 0 to 279 that corresponds to the LOAD-CARRYING CAPACITY of a tire.

Like most of you know, Load Range describes the ply rating of the tire.
It's important to remember that these are ONLY RATINGS and not the actual number of ply's like it used to be back when tires were made of cotton belts (bias). Below are the most common Load Ranges you'll see on today's trucks.
C = 6 ply rated D = 8 ply rated E = 10 ply rated

Now here's where it can get a bit confusing.
It's commonly assumed that C rated tires hold a maximum pressure of 50 PSI, that D rated tires hold a maximum pressure of 65 PSI, and E rated tires hold a maximum pressure of 80 PSI. This information is correct but only applies to a certain tire size range, or rather, section width.
Here's what you need to focus on.

LT tires that are 295mm (LT-Metric) in section width or 11.50" in section width (LT-Flotation) and narrower, will carry the commonly associated maximum pressure.
C = 6 ply rated and hold a maximum pressure of 50 PSI
D = 8 ply rated and hold a maximum pressure of 65 PSI
E = 10 ply rated and hold a maximum pressure of 80 PSI
Not so tricky I hope. So you're probably thinking to yourselves, what about the other sizes? And I'll tell you...

LT tires that are 305mm (LT-Metric) in section width or 12.50" (LT-Flotation) and wider, still carry the same ply rating/Load Range but hold a different maximum inflation pressure. The maximum inflation pressure on these wider sizes lose 15 PSI from the maximum inflation pressures above.

The new inflation pressures on these wider sizes are as follows:
C = 6 ply rated and hold a maximum pressure of 35 PSI
D = 8 ply rated and hold a maximum pressure of 50 PSI
E = 10 ply rated and hold a maximum pressure of 65 PSI

Now what about Load Index?
Like mentioned previously, Load Index is an assigned number that corresponds to the load carrying capacity. More specifically, at the maximum pressure. The assigned number or Load Index can be seen on the chart below.
*Please note that this chart only goes up to 150 as most LT truck tires today do not exceed 128.

So lets take the Load Index 123 for example.
This Load Index tells us that the corresponding load carrying capacity is 3417lbs at maximum pressure. Now it doesn't show what the maximum pressure is so we now have to go look at the Load Range on the tire we are looking at.

Taking the example of LT-Metric Sizing listed earlier (LT265/75R16/E 123R). We know the tire is 10 ply rated and is narrower than 295mm in section width which tells us that the maximum inflation pressure is 80 PSI.
By using the Load Index chart we know the 123 Load Index carries 3417lbs at maximum pressure. So from what we have discussed, we now know that the LT265/75R16/E 123R tire carries a maximum load of 3417lbs. @ 80 PSI.
Now taking the example of LT-Flotation Sizing listed earlier (31x10.50R15LT/C 109S), we know the tire is 6 ply rated and is narrower than 11.50" in section width which tells us that the maximum inflation pressure is 50 PSI.

By using the Load Index chart we know the 109 Load Index carries 2271lbs at maximum pressure. With this information we now know the 31x10.50R15LT/C 109S tire carries a maximum load of 2271lbs @ 50 PSI.

Here's where it get's fun.

A lot of people think that Load Range E tires will always carry more weight than the lower ply rated/Load Range tires. This is not always the case. Let me show you an example.

A common OE (original equipment) LT tire size is LT245/70R17/E 119S. By using what we have learned above we know that this LT tire size carries 2998lbs @ 80 PSI. Now lets look at an LT315/70R17/D 121T which is a common plus size LT tire. Again, from what we have learned above we know this tire carries 3197lbs @ 50 PSI.
So even though the OE tire we used for an example is E rated with a maximum pressure of 80 PSI, the plus size D rated tire carries more weight at a lower pressure. In other words, LOAD RANGE E doesn't always mean the tire can carry more weight at maximum pressure when compared to LOAD RANGE D at maximum pressure.

Here's where your application and uses come in.

What does this mean to you if you are upgrading from the stock E Load Rated tire with an 80psi max to a new, larger, E rated tire with a 65psi max What if your upgrading to a larger size that is D load rated?

If you do not tow much it may not matter as long as your new tire carries equal to, if not a higher, load index number.
The new tire will still be able to carry at least the same weight at 65psi as your stock tire would at 80psi.
The only real difference is the way the vehicle may handle under load. If you are accustomed to towing with 80 psi in your tires and now you are only able to tow with 65psi, your vehicles response can feel squishy or lazy and you can experience a bit more "roll" as the vehicles weight shifts in turns.

How do you tell if the E Load Rated tire you are looking to buy has a 65psi or 80psi max?
On our website we indicate all 80psi E Load Rated tires as "E1" and all 65psi E Load Rated tires as "E2" in the tire size. Same thing goes for "D" and "C" Load Rated tires.

I hope this information helps.
-Matt
__________________

Cheers,
Reg
The article was written by Matt from Discount Tire. Excellent information.

LT Tires and How They Work
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Ford Powerstroke Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 06:07 AM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.1
Garage Plus, Vendor Tools vBulletin Plugins by Drive Thru Online, Inc.

vB.Sponsors