Tire Safety Question

Tully Mars · Posted: Tue Jul 29, 2008 2:55 pm Post subject:

Okay Boys and Girls...

I have read Most.. of the tire stuff information on this site and elsewhere. But I still have a few questions.

First, I have an 84 Westy. Let's do some arithmetic on the LOAD rating issue. Forget about Reinforced Sidewall and tire pressure stuff for the time being.

Now, according to my sticker, the GROSS VEHICLE WEIGHT (GVW) on the rear axle is 2866 lbs. or 1433. GVW according to my VW owners manual is a full loaded van with a person in every seat (150 lbs. each) plus luggage. So, this is the MAX load.

Now, if you put a Passenger tire on this vehicle you need to derate it by dividing by 110% according to this thread. So... a Passenger tire with a 98 load rating of 1653 lbs. capacity is therefore de-rated to 1503 lbs.
It works. A passenger tire with 96 load rating of 1565 is de-rate to 1423. Within 10 pounds for my vehicle.

The second test for "Normal Load" does not control. If you further de-rate the tire and reduce the load of the vehicle, the MAX load still controls. Both the 96 and 98 meet the "Normal" load criteria.

Am I missing something?

Oh.. right. Tire pressure. Well, the tire pressures requirements on my vehicle sticker are for specific sizes 14" tires. I am running 15" wheels and tires so they don't seem to apply. If a tire is RATED for the LOAD at a specific PRESSURE and it meets the requirements, why would you need to increase it to meet these higher pressures???
(Mine are like 46 rear and 36 front)

Salud...

Tully Mars
_________________
I'm a man. But I can change.
If I have to.
I guess.
_______
84 Wolfsburg Westfalia
Hobie Cow

mightyart · Posted: Tue Jul 29, 2008 3:01 pm Post subject:

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GWTWTLW · Posted: Tue Jul 29, 2008 3:04 pm Post subject:

That's why!!!
_________________
89 Syncro Westy - GW 2.5, now with a double knob job
@gwtwtlw

Jamos · Posted: Tue Jul 29, 2008 3:27 pm Post subject:

well said mightyart..
Shocked

this is one of those topics that has a lot of variables and can insight a lot of different opinions

the fact that VW recommends much different pressures for different sized 14" tires leads me to believe that if it had been fitted with 205/65 15 tires from the factory, that they would have suggested yet another inflation pressure for that specific size.

so to say "my sticker says 39 front, 48 rear, (which was the requirement for the 205/70 14 I believe) so that tire won't work" does not apply for a different sized tire.

Did VW fit vanagons in SA with 15" wheels from the factory? What size & psi did they recommend if so? Anyone know?
_________________
'86 Wolfy Westy Weekender
2020 Audi Q5

Randy in Maine · Posted: Tue Jul 29, 2008 3:40 pm Post subject:

PDXWesty · Posted: Tue Jul 29, 2008 4:06 pm Post subject:

If you look at any tire manufacturer spec sheet, the same tire with the same construction and same PSI rating will have different loads depending on tire size. It all has to do with the height of the tire sidewall and the footprint the tread sees on the ground. The bigger the footprint, generally the higher the "total" tire load rating.

With that said, there are so many variables that each tire in each size range should be evaluated individually. One size may meet the rating but another size for the same tire may not.

http://www.tirerack.com/tires/Spec.jsp?make=General&model=Grabber+AT+2&tirePageLocQty=

On a side note, my van recently weighed in at a whopping 6300 lbs fully loaded with gear, ice chests, dog and two of my buddies riding with me. Believe the weight...it's true.

.

levi · Posted: Tue Jul 29, 2008 4:16 pm Post subject:

Wildthings · Samba Member Joined: March 13, 2005 Posts: 50338

Nice to know that the original Michelins on my van, 205/70R14 reinforced, with a 97 load rating didn't meet specs. Still the best riding, best handling, and longest lasting tires I have had on any of my Vanagons out of the ten or so sets of tires that I have run by now. If I could still get them that is what I would run, and leave you guys to debate what is second best.

Jamos · Posted: Tue Jul 29, 2008 7:15 pm Post subject:

Randy in Maine · Posted: Tue Jul 29, 2008 7:21 pm Post subject:

So what is the difference in pressure?

I don't know. I don't have that sticker.

Wildthings · Samba Member Joined: March 13, 2005 Posts: 50338

For the 185R14 6 ply the rears are 53psi

and

for the 205/70R14 reinforced the rears are 40

Jamos · Posted: Tue Jul 29, 2008 9:47 pm Post subject:

Randy in Maine · Posted: Wed Jul 30, 2008 4:27 am Post subject:

Petervw · Posted: Wed Jul 30, 2008 5:41 am Post subject:

Michelins, no matter what passenger tire they produce, are designed to ride soft...2 or 3 ply is just playing with words...heres a good example of being a tire "kicker" anybody can do...go into your tire store and "feel and flex" the side walls of for example the 2 0r 3 ply Mich.LTX and then compare it to for example the Goodyear Triple Tred...although this tire is rated 2ply, but the plys are much "thicker" which makes the sidewall extremely stable and also good for up to 44lbs...another slightly different example..the Toyo "Open Country series" I have seen on some commercial Dodge/Frieghtliner 2500s...(one driver told me that these tires were more suited for the pot holed street driving he experienced)...proper tire "pressure" for the application can be determined by simple tests (google)...generally speaking, you want the tire tred to "sit evenly across" the pavement as to prevent any abnormal wear and to promote good brakeing

mightyart · Posted: Wed Jul 30, 2008 5:48 am Post subject:

The tire debate is really about two things, people not wanting to spend the extra money on the right tires, or trying to justify keeping the tires they just bought.
If you have mushy passenger tires on your van it is costing you alot more in gas then you would be saving on tires these days.

mightyart · Posted: Wed Jul 30, 2008 5:52 am Post subject:

bucko · Posted: Wed Jul 30, 2008 6:52 am Post subject:

I'll be happy to add my ignorance to this tire issue. About 7 months ago, I had a blowout on one of my Continental tires. Not the tires fault, as I had imported this Westy from Germany, and all 4 tires showed some sidewall cracks from age. I went to a Local Dallas tire store and asked for 4 new tires. The sales rep got on his computer and came up with a set of 4 tires and said he'd have them in a day. The follwoing day they were installed.

I now have a very "mooshy" ride, with lots of sidewall flex. After visiting with Mightyart and seeing the tires on his Westy, I'm convinced I was sold tires that are not efficiantly rated (load wise) for this Vanagon Westy. I plan to have a new set installed very soon, even though these tires have only a couple of thousand miles on them. In no way do I want my Vanagon to be as the pictures above, due to my stupidity. I should have done my own homework, based on the good advice provided here.

To all that are buying tires soon (or see this thread in a search function), use this information to your advantage. Don't trust the tire saleman at the tire store in all cases. I doubt they install tires on Westys that often, so they are most likey going to get you to buy whatever they can get on hand quickly.

Lesson learned for me.
_________________
Current VW drives: 1984 Westfalia

Past VW drives: 1967 Beetle, 1973 Beetle, 1977 Bus, 1971 Military Type 181

Petervw · Posted: Wed Jul 30, 2008 7:25 am Post subject:

mightyart · Posted: Wed Jul 30, 2008 7:34 am Post subject:

Petervw · Posted: Wed Jul 30, 2008 7:49 am Post subject:


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