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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50351
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Posted: Wed Oct 30, 2013 7:54 pm Post subject: |
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denwood wrote: |
That reinforced tire carried 1580lbs at 40psi. It does not get de-rated as it is a specially reinforced passenger tire. So 40 psi (on the OE tires) at the rear gets you to 3160lbs (1580 x 2) over two tires. Guess what your vehicles rear GAWR is? 3042lbs. |
Check this link:
http://www.google.com/url?sa=t&rct=j&q=&am...9444,d.cGE
They use as an example of a passenger tire needing to have its load rating reduce when used on an SUV or other light truck a 305/50R20 tire with a 3086# load rating at 50psi. This is an XL tire. From the best I can determine the paragraph on load reduction comes straight from the Tire and Rim Association as many tire companies use the same exact example.
If you have found something of authority that says differently I would like to see it. |
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geodude Samba Member
Joined: May 24, 2012 Posts: 372 Location: Sacramento
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Posted: Wed Oct 30, 2013 8:00 pm Post subject: |
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I'm not sure that equation is correct. The maximum load rating is specified for a certain pressure. For Standard Load it's 35 psi, for XL it's 41 psi, for Load Range C it's 50 psi, etc. The max load doesn't really play into this. If You have an XL tire for instance that has a load index of 98 that rating is at 41 psi, not max inflation. That is likely why the late vans with the alloys spec'd 40 psi rear, since they were using 97R (same as XL) tires (they got the tire closest but slight higher capacity than needed). Now the capacity does go up with pressure, but you don't want to get near max pressure or you risk tire damage. I think some people have had blowouts since they thought they had to have xx amount of pressure regardless of what the max load pressure was and were putting in 50 psi (or whatever) in a tire meant to run at 41 or less.
So since capacity is proportional to pressure the equation would be more like max load pressure psi / max rated load x needed capacity = needed inflation psi. _________________ 1988 GL Camper
1991 Multivan — the basket case |
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Jon_slider Samba Member
Joined: April 11, 2007 Posts: 5091 Location: Santa Cruz, Crowdifornia
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Posted: Wed Oct 30, 2013 8:10 pm Post subject: |
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Thank You!
here is that formula
(OE tire max load) X (Sticker recommended PSI) / (OE tire max PSI) X (New tire max PSI) / (New tire max load) = new tire recommended inflation
And thanks for using specific tire examples of 14" tires that meet Vanagon specs. Totally On topic and very helpful. _________________ My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco
Last edited by Jon_slider on Wed Oct 30, 2013 9:26 pm; edited 1 time in total |
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davevickery Samba Member
Joined: July 16, 2005 Posts: 2887 Location: Fort Collins, CO
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Posted: Wed Oct 30, 2013 8:55 pm Post subject: |
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Wildthings wrote: |
denwood wrote: |
That reinforced tire carried 1580lbs at 40psi. It does not get de-rated as it is a specially reinforced passenger tire. So 40 psi (on the OE tires) at the rear gets you to 3160lbs (1580 x 2) over two tires. Guess what your vehicles rear GAWR is? 3042lbs. |
They use as an example of a passenger tire needing to have its load rating reduce when used on an SUV or other light truck a 305/50R20 tire with a 3086# load rating at 50psi. This is an XL tire. From the best I can determine the paragraph on load reduction comes straight from the Tire and Rim Association as many tire companies use the same exact example.
If you have found something of authority that says differently I would like to see it. |
I think wildthings is proibably right. I've seen similar examples and the derating rule refers to "passenger car tires" without specifically excluding XL or R tires from that definition.
So I wonder when the derating came about. If it was after 1991 that would makes sense, because if that 97R tire was required to be derated it would not have met the syncro weight. |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9936 Location: Orbiting San Diego
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Posted: Wed Oct 30, 2013 9:15 pm Post subject: |
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Agreed, the XL and RF should be treated as passenger car tires as far as de-rating goes.
I too have wondered exactly when the de-rating came into effect. I find it a little surprising that VW went with the 205/70/14 97R at all on the Syncro. Especially when you put it in the context of the other tires listed on the Syncro door sticker. The 205R14C is massively higher load rated for example.
Mark
davevickery wrote: |
I think wildthings is proibably right. I've seen similar examples and the derating rule refers to "passenger car tires" without specifically excluding XL or R tires from that definition.
So I wonder when the derating came about. If it was after 1991 that would makes sense, because if that 97R tire was required to be derated it would not have met the syncro weight. |
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Jon_slider Samba Member
Joined: April 11, 2007 Posts: 5091 Location: Santa Cruz, Crowdifornia
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Posted: Thu Oct 31, 2013 8:50 am Post subject: |
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If you look at this chart
http://www.roadhaus.com/tires/OE%20Tire%20Load%20Inflation%20Table.html
you will see VW used 1580 as a rear load inflation target on both Syncros and 2wd vans at different times. You will also see VW used rear axle load inflations as high as 1710 lbs for 2wd, and as high as 1750 lbs for a syncro. Those values are higher than the rear GVAWR, which for a 2wd was 1433, and for a Syncro was 1521.
Here is info about the use of XL tires, and the 9% derating of passenger tires. It does not say to derate XL tires. In fact it says the tire with a 1580 max load rating was the lowest XL rated tire VW used.
===
http://www.roadhaus.com/tires/guideline.html
"The 205/70R14 97R VW used was a "special" passenger car tire.
This might lead some people to assume they can use passenger car tires instead of Light Truck tires on a Vanagon.
However there are two factors to consider.
1) This OE tire had a "Reinforced sidewall. In today's tire market , passenger car tires with a reinforced sidewall will have either a XL or RF designation.
Example 305/50R20 XL or 305/50R20 RF.
Light Truck tires by the nature of their design already have reinforced sidewalls and thus the XL & RF designations do not apply.
2) The second issue and perhaps the least understood, in using a passenger Car tire on a Light truck application is the 9% rule.
What the heck is this ....
Using passenger car tires on light trucks should be approached with caution. The varied service that a light truck undergoes and because these vehicles have a higher center of gravity and greater probability of being overloaded than passenger cars means that the rated load-carrying capacity of a passenger car tire used on it is reduced. When referencing a passenger car tire for light truck use, decrease the tires load capacity by 9%"
===
At different times and with different tires, VW used Front load targets on a Syncro of 1365, 1433, 1465, and 1480 pounds. I was not aware that those were ever the GVAWR for the front of a Van.
http://www.roadhaus.com/tires/guideline.html
"Vanagon & Camper ... GAWR Rear 2866 / 2 = 1433 lbs on each rear wheel if loaded to capacity
Syncro Vanagon & Camper ... GAWR Rear 3042 / 2 = 1521 lbs on each rear wheel if loaded to capacity"
VW used load inflations for the rear of a Syncro, whose rear GVAWR was 1521, of 1580, and also 1750, at different times and with different tires. My point is the load inflations exceed the axle ratings, they are not the same.
But you can skip all the load table concerns, and all the derating concerns, by avoiding P and XL tires, and using C or D rated tires instead. And you can extrapolate the inflation for the new tire, based on the door sticker, without ever needing a load table. _________________ My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco |
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crazyvwvanman Samba Member
Joined: January 28, 2008 Posts: 9936 Location: Orbiting San Diego
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Posted: Thu Oct 31, 2013 10:37 am Post subject: |
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Larry did a great thing when he researched and wrote his famous tire blog but some of what is there is simply opinions, which he admits. It has a lot of good info but some of it is less so IMHO. If no one can cite a real source for not treating XL and RF passenger tires as passenger tires then I will treat them as passenger tires and de-rate them until such evidence comes into play.
Mark |
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Randy in Maine Samba Member
Joined: August 03, 2003 Posts: 34890 Location: The Beach
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Posted: Thu Oct 31, 2013 10:38 am Post subject: |
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I just spoke with John the Technical Guy at Kumho Tires USA (800) 445-8646.
He told me that the Kumho 857 series tires are indeed a suitable tire for use in a VW bus or vanagon. Nice and stiff in the sidewall and able to support some serious weight. Some trailer tires do have construction or desgin details that make them unsuitable for use as car or truck tire and those all "trailer only tires" have the prefix of "ST" for the restrictions to be used only for trailer use. |
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regis101 Samba Member
Joined: July 28, 2005 Posts: 2078 Location: Livermore, Ca
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Posted: Thu Oct 31, 2013 10:41 am Post subject: |
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I'll take science over seat-of-the-pants any day.
My pants are worn out _________________ Peace, Regis |
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geo_tonz Samba Member
Joined: August 01, 2012 Posts: 1472 Location: Courtenay, BC, CANADA
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Posted: Thu Oct 31, 2013 10:41 am Post subject: |
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Randy in Maine wrote: |
I just spoke with John the Technical Guy at Kumho Tires USA (800) 445-8646.
He told me that the Kumho 857 series tires are indeed a suitable tire for use in a VW bus or vanagon. Nice and stiff in the sidewall and able to support some serious weight. Some trailer tires do have construction or desgin details that make them unsuitable for use as car or truck tire and those all "trailer only tires" have the prefix of "ST" for the restrictions to be used only for trailer use. |
Cool, Thanks!
I emailed them but didn't receive a response and left it...should have dialed them up! _________________ ---------------------------------------------------
"Ron Burgundy": 1991 Vanagon Multivan (Weekender) 2.1L Auto - Driver/Camper |
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denwood Samba Member
Joined: July 29, 2012 Posts: 1047 Location: Thunder Bay, Ontario, Canada
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Posted: Thu Oct 31, 2013 3:30 pm Post subject: |
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Chatting with Jon over pm's, and reading over my own post on the load tables examination, I'm thinking the equation:
(OE tire max load) X (Sticker recommended PSI) / (OE tire max PSI) X (New tire max PSI) / (New tire max load) = new tire recommended inflation
will consistently deliver PSI ratings that may slightly exceed the load tables, but not under. To understand the p-metric, reinforced, iso-metric and LT load tables, and the 10 pages of tech stuff associated is all there in the TOYO document, but easy to make a mistake interpreting the volume of information there. That equation though is pretty straightforward. I'd suggest we throw up an excel sheet link, run the tires through it and cross check with the load tables. Anyone posting a question can decide if they want to wade through the technobabble, or just plug the numbers into the spreadsheet to assess their options.
Then the next person who asks gets the excel link and a smile _________________ Cheers,
Dennis Wood
The Grape |
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Jon_slider Samba Member
Joined: April 11, 2007 Posts: 5091 Location: Santa Cruz, Crowdifornia
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devesvws Samba Member
Joined: January 05, 2004 Posts: 1540 Location: madison va
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canasync Samba Member
Joined: June 28, 2010 Posts: 656 Location: BC
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Posted: Thu Nov 28, 2013 2:41 pm Post subject: |
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devesvws wrote: |
is this a defect?? Front tire depression with about 20k on them 1yr 8 months old. hankook ra08 |
Oddly enough that is quite common except that most people never notice.
I have had this both on cheap tires as well as high end expensive ones and on a variety of vehicles, not just vans. If your worried check with your tire place but they will probably tell you not to worry about it. _________________ 1987 Syncro
3 knobs
PumpeDüse TDI (17mm Garret Turbo, bigger injectors, stage 4 malone tune, intercooled)
Cruise Control
Remote Start/locks
Custom Lift
Custom Bumpers with receivers
Coast Mountain Hightop - Comming Soon
1985 2wd Vanagon Pre-runner in the making
soon to be powered by 2.5L Subaru
Custom Lift |
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devesvws Samba Member
Joined: January 05, 2004 Posts: 1540 Location: madison va
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davevickery Samba Member
Joined: July 16, 2005 Posts: 2887 Location: Fort Collins, CO
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junichi Samba Member
Joined: September 12, 2005 Posts: 749 Location: brentwood bay, bc
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Posted: Fri Feb 07, 2014 4:23 pm Post subject: Kumho road venture AT kl78 |
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Found these on the kumho canada site. Not listed in 14" on tire rack site but available at my local kumho dealer. Seem to meet the specs for load and the shop says they will mount on the 5.5 inch rim. It's a 27x8.5 LT tire and looks prettyy nice. Price is $130 each, which is way cheaper than BFG or yoko Y370 that we get here. _________________ 1964 Kombi- http://www.thesamba.com/vw/forum/viewtopic.php?t=640048
Sold: 1985 Transporter Doka,1978 Westfalia, 1975 bay x 2, 1986 syncro vanagon, 1965 beetle, 1980 vanagon, 1967 deluxe bus, 1988 golf |
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PDXWesty Samba Member
Joined: April 11, 2006 Posts: 6247 Location: Portland OR
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Posted: Fri Feb 07, 2014 4:31 pm Post subject: Re: Kumho road venture AT kl78 |
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junichi wrote: |
Found these on the kumho canada site. Not listed in 14" on tire rack site but available at my local kumho dealer. Seem to meet the specs for load and the shop says they will mount on the 5.5 inch rim. It's a 27x8.5 LT tire and looks prettyy nice. Price is $130 each, which is way cheaper than BFG or yoko Y370 that we get here. |
WHAT MODEL TIRE? I CAN'T FIND ANY ON THE US SITE. _________________ 89 Westy 2.1 Auto |
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junichi Samba Member
Joined: September 12, 2005 Posts: 749 Location: brentwood bay, bc
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davideric9 Samba Member
Joined: January 21, 2009 Posts: 1002 Location: Oakland CA
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Posted: Sat Feb 08, 2014 9:01 am Post subject: |
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I just bought these tires:
LANDSAIL LS288 RADIAL ALL SEASON XLPLY BW - P205/70R14 98H
$62 each with free shipping. They seem to meet the required specs for the vanagon 2wd. They are rated XL on the sidewall. I'll let you know how they feel once they are installed.
Did I get the wrong tires? Do these meet spce, or close to it? I have BFG AT on the syncro, and they have been a standard goto tire for a long time AND the don't meet spce, so I figured close enough is not bad... (plus supporting 4 vans they don't all get the top of the line stuff, too much money for my blood). _________________ 1987 Syncro Westfalia, stock (bought 1994)
1986 Syncro Westfalia SVX, 3 knob (bought 2008)
1987 Westfalia (bought 2010)
1988 Wolfsburg GL (bought 2012) |
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