Reply
 
Thread Tools Search this Thread Display Modes
 
Old 02-25-2015, 08:01 PM   #15
4 Rivet Member
 
1975 27' Overlander
High River , Alberta
Join Date: Aug 2006
Posts: 393
Quote:
Originally Posted by TCwheels View Post
The 55s will actual fit my wheels better than the stock 60s, therefore gaining stability two ways. Load rating is easily over what I need for my 20' - even wet.

Right - I noticed you stayed with the same section width, and just went down in profile.

Good to know that the 235s fit your wheels well; Lexus seems to use 7.5 inch wide wheels, so that bodes well for using 255s on the 8" wide wheels on the Pilot. I raised this concern because I once had snow tires that were a bit wide for a set of aftermarket steel wheels, and I didn't like the way the car felt in crosswinds at highway speeds.

I'm coming up with a 3.2% speedometer error, but math isn't my strong suit. In any event it's a small error; what might matter more to the OP is the loss of load rating. The GVWR of the RX is about 5,600 lbs, or about 500 lbs less than the Pilot.
__________________

__________________
AlbertF is offline   Reply With Quote
Old 02-25-2015, 10:53 PM   #16
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 690
Need to get your facts straight

Load Range basically replaces the old Ply Rating
Load Range for LT and ST type tires start at "C" and move up to D then E.
As you move to Commercial or Truck tires it continues to F G etc.

Load Index is a number such as 102 or 114 that can be converted to a range of pounds load capacity for the tire under consideration.
Here is the table courtesy of Tire Rack

Since load is carried by the air and not the tire structure the more air volume and more air pressure you have the greater the load capacity.
This means that with the same section and rim diameter the higher the Aspect Ratio the greater the air volume which means more load capacity.

Alternately holding Aspect constant but increasing the Section width will increase the air volume and also the load capacity.
__________________

__________________
Retired tire engineer (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Old 02-26-2015, 06:26 AM   #17
2 Rivet Member
 
2011 19' Flying Cloud
Farmington Hills , Michigan
Join Date: Nov 2014
Posts: 34
That logic makes sense but there must be something else besides the air volume to the equation. The Michelin Primacy tires that were on the Pilot had pretty poor traction in the snow and their load rating was 102 for the 235 60 18s. The same size in the Mastercraft HSX had a load rating of 107. I picked up the Mastercraft 255 55 18 yesterday as I heading north to my cabin today and really did not want to make another trip on my old tires. I was tempted to go with thee the Michelin LTX in 245 60 but had a hard time pulling the trigger on the extra $300+ dollars. We'll see how my decision holds up. Thanks for all the advice!
__________________
tobutton is offline   Reply With Quote
Old 02-26-2015, 01:59 PM   #18
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 690
Quote:
Originally Posted by tobutton View Post
That logic makes sense but there must be something else besides the air volume to the equation. The Michelin Primacy tires that were on the Pilot had pretty poor traction in the snow and their load rating was 102 for the 235 60 18s. The same size in the Mastercraft HSX had a load rating of 107. I picked up the Mastercraft 255 55 18 yesterday as I heading north to my cabin today and really did not want to make another trip on my old tires. I was tempted to go with thee the Michelin LTX in 245 60 but had a hard time pulling the trigger on the extra $300+ dollars. We'll see how my decision holds up. Thanks for all the advice!
Would help if complete info was provided. i.e. the actual size and inflation you were looking at when you thought you found the associated Load Index.
Also if we are talking about Load Capacity I don't understand why people are introducing Snow Traction. The is not part of the Load Calculations.

Michelin Primacy MXM4 P235/60R18 has a Load Index of 102 according to Tire Rack. This is a standard load (35 psi) rated tire.

The Mastercraft HSX in a "Euro-Metric" i.e. non-P type tire and is rated XL for 50 psi not the 35 psi standard load passenger tire. Mastercraft is playing games telling people that the metric size and P-Metric size are the same. When pressed the rep will admit their tires are not identical in size to P type tires.

You made to common mistake of not looking at the complete tire size nomenclature.
__________________
Retired tire engineer (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Old 02-27-2015, 05:59 AM   #19
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 624
Quote:
Originally Posted by tobutton View Post
That logic makes sense but there must be something else besides the air volume to the equation. The Michelin Primacy tires that were on the Pilot had pretty poor traction in the snow and their load rating was 102 for the 235 60 18s. The same size in the Mastercraft HSX had a load rating of 107........
Ah, but the 102 Michelin was a Standard Load (SL) which has its max load carrying capacity rated at 35 psi, and the 107 Mastercraft was an Extra Load (XL) which has its max load rated at 41 psi - ergo, the air volumes are different.
__________________
CapriRacer is offline   Reply With Quote
Old 03-01-2015, 07:04 PM   #20
Rivet Master
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 10,840
Capri', I know what is in the tires carries the load whether it is air, nitrogen or beer (what a waste unless you like to drink hot beer as you let it out of the valve stem). But don't Michelin Rib tires have steel belts in the sidewall and will carry some of the load? I don't think they are appropriate for anything but what they are designed for—trucks that stay in urban areas and never go very fast and are made to be recapped once the tread wears. Some people use them on their trailers and are happy with them, though I think the ride is too hard for a trailer or a tow vehicle.

This doesn't really matter in the real world, but I'm curious about it.

Gene
__________________
Gene is offline   Reply With Quote
Old 03-02-2015, 06:18 AM   #21
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 624
Quote:
Originally Posted by Gene View Post
Capri', I know what is in the tires carries the load whether it is air, nitrogen or beer (what a waste unless you like to drink hot beer as you let it out of the valve stem). But don't Michelin Rib tires have steel belts in the sidewall and will carry some of the load? I don't think they are appropriate for anything but what they are designed for—trucks that stay in urban areas and never go very fast and are made to be recapped once the tread wears. Some people use them on their trailers and are happy with them, though I think the ride is too hard for a trailer or a tow vehicle.

This doesn't really matter in the real world, but I'm curious about it.

Gene
Gene,

First, by definition belts appear under the tread only - not in the sidewall.

Second, most Michelin tires do NOT have steel body plies (which is what I think you were alluding to).

However, Michelin does produce tires that do have steel body plies. Pretty much all of their medium truck tire lines are steel body plies. They also produce an abbreviated line of LT tires with steel body plies - the XPS, which only comes in a rib pattern. (Note: Michelin has other LT designs that have polyester body plies, some of which are rib designs).

And lastly, the material used in the sidewall is irrelevant. What is important is the strength. A LOT of polyester can be stronger then a LITTLE bit of steel.

And you are correct, their abbreviated LT line called the XPS Rib was designed for commercial usage where ride is NOT a consideration and where retreadability offsets the initial cost.
__________________
CapriRacer is offline   Reply With Quote
Old 03-02-2015, 10:33 AM   #22
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 690
Quote:
Originally Posted by CapriRacer View Post
Gene,

First, by definition belts appear under the tread only - not in the sidewall.

Second, most Michelin tires do NOT have steel body plies (which is what I think you were alluding to).

However, Michelin does produce tires that do have steel body plies. Pretty much all of their medium truck tire lines are steel body plies. They also produce an abbreviated line of LT tires with steel body plies - the XPS, which only comes in a rib pattern. (Note: Michelin has other LT designs that have polyester body plies, some of which are rib designs).

And lastly, the material used in the sidewall is irrelevant. What is important is the strength. A LOT of polyester can be stronger then a LITTLE bit of steel.

And you are correct, their abbreviated LT line called the XPS Rib was designed for commercial usage where ride is NOT a consideration and where retreadability offsets the initial cost.
Gene
I know you asked C-Racer and specifically mentioned Michelin but Bridgestone and other major tire companies make similar "Commercial" or "Medium duty" tires with steel body ply. The Bridgestone steel body tire is the R250. You can check with Tire Rack for other possible suppliers.

The technical portion of Capri's reply is accurate and correct no matter the brand.
__________________
Retired tire engineer (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Old 03-02-2015, 11:04 AM   #23
Rivet Master
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 10,840
I am told the Rib has a steel mesh in the sidewall, not steel cord. I don't know what the difference is, and I can see a cord or mesh of other substances could be stronger. It would seem to me that would provide some small amount of support, but I am not a tireman or racer of anything, and that is why I asked the question.

I thought all Michelins had a steel cord in the tread plies. Since a "cord" could mean steel wires woven into a mesh, I think mesh is probably a more accurate term. When I have had to fix a flat in remote places, I ran into steel something (really a mesh I think) when I reamed out the hole and pushed the plug through. It made it much harder to get through the tread. These were on LTX tires. By the way, although plugs are not as good as a patch inside, when in extremis, a plug works fine. I haven't had to do this often (twice I can remember in 25 or more years), but the plugs held for the life of the tire and never leaked. I always carry a tire kit with me if case I have to repair a tire myself.

Thanks for the responses. I have learned more about tires than I ever wanted to know since we bought the trailer. Now I can misinform people and throw technical terms around just like any other guy.

Gene
__________________
Gene is offline   Reply With Quote
Old 03-03-2015, 03:51 AM   #24
Vintage Kin
 
slowmover's Avatar
 
Fort Worth , Texas
Join Date: Nov 2006
Posts: 7,583
Images: 1
The XPS and r250 are the "ultimate" trailer tires as I see it (where the rating is a good match for that vehicle).

Bluto uses the former and I plan to use the latter on my TT this year.
__________________
1990 35' Silver Streak Sterling; 9k GVWR.
2004 DODGE Cummins 305/555; 6-manual; 9k GVWR.
Hensley Arrow. 9-cpm solo, 15-cpm towing
Sold: Silver Streak Model 3411
slowmover is offline   Reply With Quote
Old 03-03-2015, 05:03 AM   #25
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 624
Quote:
Originally Posted by Gene View Post
I am told the Rib has a steel mesh in the sidewall, not steel cord. I don't know what the difference is, and I can see a cord or mesh of other substances could be stronger. It would seem to me that would provide some small amount of support, but I am not a tireman or racer of anything, and that is why I asked the question.

I thought all Michelins had a steel cord in the tread plies. Since a "cord" could mean steel wires woven into a mesh, I think mesh is probably a more accurate term. When I have had to fix a flat in remote places, I ran into steel something (really a mesh I think) when I reamed out the hole and pushed the plug through. It made it much harder to get through the tread. These were on LTX tires. By the way, although plugs are not as good as a patch inside, when in extremis, a plug works fine. I haven't had to do this often (twice I can remember in 25 or more years), but the plugs held for the life of the tire and never leaked. I always carry a tire kit with me if case I have to repair a tire myself.

Thanks for the responses. I have learned more about tires than I ever wanted to know since we bought the trailer. Now I can misinform people and throw technical terms around just like any other guy.

Gene
Gene,

It's a little difficult to explain, but the term "cord" means a cable-like, or rope-like, or thread-like thing, and not a mesh. There are a lot of technical reasons why tire manufacturers use cord and not mesh, but they involve a long discussion of manufacturing techniques.

In the belts, there are 2 that layer over top of one another and form a grid like series of layers that sort of resembles a mesh, except they are not interwoven. It is NOT like a wire mesh fence.
__________________
CapriRacer is offline   Reply With Quote
Old 03-03-2015, 08:21 AM   #26
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 690
Quote:
Originally Posted by Gene View Post
I am told the Rib has a steel mesh in the sidewall, not steel cord. I don't know what the difference is, and I can see a cord or mesh of other substances could be stronger. It would seem to me that would provide some small amount of support, but I am not a tireman or racer of anything, and that is why I asked the question.

I thought all Michelins had a steel cord in the tread plies. Since a "cord" could mean steel wires woven into a mesh, I think mesh is probably a more accurate term. When I have had to fix a flat in remote places, I ran into steel something (really a mesh I think) when I reamed out the hole and pushed the plug through. It made it much harder to get through the tread. These were on LTX tires. By the way, although plugs are not as good as a patch inside, when in extremis, a plug works fine. I haven't had to do this often (twice I can remember in 25 or more years), but the plugs held for the life of the tire and never leaked. I always carry a tire kit with me if case I have to repair a tire myself.

Thanks for the responses. I have learned more about tires than I ever wanted to know since we bought the trailer. Now I can misinform people and throw technical terms around just like any other guy.

Gene
Gene, Just so you get overloaded with more tire info here is a basic page on tires.

Video on manufacturing from Hankook

Michelin movie. Note the cord is not "woven" into a mesh as is the cotton in your T-shirtbut the cords are parallel to each other

Agriculture and Mining tires are made in the process that is similar to NASCAR or F1 racing tires. Note the "Calendering" process shows cords that are parallel to each other and not woven into a mesh.

A tire builder from 1934 would recognize most of today's process other than the difference between Bias and Radial construction.

Tire manufacturing in Africa.

Just an old school video of how tires are made

The few tires I personally built during my early training were the "Old School" type. This hands on training gave me a good understanding with the professional builders did every day with the designs I was to be developing.


Enjoy
__________________
Retired tire engineer (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Old 03-03-2015, 01:25 PM   #27
Rivet Master
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 10,840
Ahhhhrgghhh! TMI. I don't want to build my own tires. I appreciate all the information, but decided decades ago I didn't want to be an engineer. It interferred with drinking, girls and I had to go to class. I hated calculus. I can't draw a straight line. Physics was taught by people who couldn't master English (and they were probably born here back then). Chemistry could have been interesting, but they managed to make it dense and boring. Hooray for liberal arts!

Now I know more about cords and mesh and if someone wants to bring me tires cut apart, it would be interesting. I do like to know how things work. But our decades long love of Michelin LTX tires has been confirmed by using them without incident (except for a rare nail, screw or broken chain link—only steel wheels are immune). I keep hoping these tire threads will provide me with something new and useful to my life, but we have pretty much exhausted the subject.

Roll on friends….

Gene
__________________
Gene is offline   Reply With Quote
Old 03-04-2015, 07:18 AM   #28
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 690
Quote:
Originally Posted by Gene View Post
Ahhhhrgghhh! TMI. I don't want to build my own tires. I appreciate all the information, but decided decades ago I didn't want to be an engineer. It interferred with drinking, girls and I had to go to class. I hated calculus. I can't draw a straight line. Physics was taught by people who couldn't master English (and they were probably born here back then). Chemistry could have been interesting, but they managed to make it dense and boring. Hooray for liberal arts!

Now I know more about cords and mesh and if someone wants to bring me tires cut apart, it would be interesting. I do like to know how things work. But our decades long love of Michelin LTX tires has been confirmed by using them without incident (except for a rare nail, screw or broken chain link—only steel wheels are immune). I keep hoping these tire threads will provide me with something new and useful to my life, but we have pretty much exhausted the subject.

Roll on friends….

Gene
OK short answer
"mesh" or "cloth" implies cords being assembled at right angle to each other. You don't get that in tires.
__________________

__________________
Retired tire engineer (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tires...Tires...Tires Bob Thompson Tires 277 07-30-2015 02:30 PM
tires radials or bias ply tires larry b Tires 22 06-27-2010 06:36 PM
Tires ready to blow out! Should Marathon tires be outlawed? marchesi Tires 21 08-22-2009 11:11 AM
Help tires, tires, tires. jimmini Tires 9 10-18-2008 08:54 PM
Tires, anybody ever heard of Specialty Tires of America? lebolewis Tires 3 06-08-2006 05:11 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 02:34 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.