Tire load rating story and request for advice

[gringoloco2000]

I posted this on vwvortex also. This is my first posting here. Be easy on me. Important questions are at the bottom.

I went to Sam's Club today to get the tires rotated since it is cheap and they have done it before. I have a V8 with 19" wheels. It only costs $16. I went back to pick up the truck and they said that the tires I bought about a month ago are dangerous and should be replaced. They said the load rating of my new tires are 105 and that the T-Reg needs 107. They of course were anxious to sell me tires for $1000 even though I bought new tires a month ago.

So, the tires I bought are Kuhmo STX K12s and they are a bit wider than the stock ones. They are 285/45/19. I read reviews and they sounded pretty good. Saw people with them on Suburbans and Tahoes, so I figured that weight would not be an issue. Never really researched the load rating.


After hearing the sales pitch at Sams today on the load balancing, I did some research. I could not find the normal load ratings even on the Kuhmo site, but they do list the STX K12s for the Touareg (Kumho Tire USA, Inc.). I found some discussions on ClubTouareg.com where some people said that VW put 105 load rated tires on it from the factory. Others had 106. So where did the rocket scientists from Sams Club get their info?


Questions:
1) The load rating from the Kuhmo site says they are rated "Max load single - 2149lbs", what the hell does that mean? 2149lbs per tire or on 4 tires? (some sites have it listed as XL)
2) Is my family in danger with these tires on the truck?


Sorry for the diatribe. All advice is appreciated.

[JKUCSMA]

Stock tires are 2094lbs.on the V6,2205lbs.for V8.Some are a little less,so your close.

[AndrieK]

The ratings are per tyre at max pressure. What they mean with single is one tyre per side on the axle. In other words, if you have a truck with two tyres on each side on the rear axle (4 tyres on the rear axle) the load rating per tyre is slightly less. (You can't carry double the load with 4 tyres on the rear axle.)

105 = 925kg (2039lbs.)
107 = 975kg (2149lbs.)
Max pressure is normally specified on the tyre and is in the range of 350kPa (50.7psi).

So with a 105 rated tyre, you can carry 8157lbs on 4 tyres. I think you'll find that this is quite a bit more than the GVM of the vehicle.

You do the math...

[gringoloco2000]

I guess I did not make the connection from the Kuhmo rating of 2149 to the chart. So, as suspected, the idiots at Sam's Club were wrong. I guess they just wanted to sell me new tires and refuse me rotate and balance. Thanks for the replies.

[Mike's Panzer]

They were not wrong. They were being careful. The liability in selling underrated tires is off the charts. Walmart and Sam's have been sued enough to make them careful. It's not a good idea to under buy tires. You will probably be fine with these tires, but realize that you compromised safety in putting them on.

[AndrieK]

Hey Mike, I disagree. I don't believe he's compromising safety by putting these tyres on.

The SA spec V8 has a GVM of 3000kg. (NA spec might vary. It's vehicle specific, so, gringoloco2000, I suggest you do a check.) I know the max load distribution is specified in the owners manual, but since I don't have a V8 or an owners manual handy, lets assume the split is 40/60 front/rear. (Again, you can confirm for your model.) That means VW allows you 1800kg on the rear axle, which is 900kg per wheel. For a 50/50 distribution, the load per tyre is 750kg.

A 105 rated tyre can handle 925kg, so the tyre is still safe. If you ever do overload the tyre and you have a failure, I'll bet it's because of underinflation and not the actual load.

I know suing is a national sport in the US, so maybe they're just trying to cover their backsides, but I still think they're overdoing it a bit.

[Mike's Panzer]

These tires aren't going to blow out at the first corner. Shops are just getting very sensitive about putting lower than spec-ed tires on a vehicle. The big chains have been a target for so long they quit taking chances. Watch them torque the bolts, and then check them twice before handing the keys back. It's the same with TPMS, a top shop will only put them back to factory condition. It's self preservation.

[gringoloco2000]

Yes, we are sue happy here. If you spill hot coffee on yourself, you can get millions.

Considering the evidence I have gathered, Sam's Club was operating in an abundance of stupidity and not caution. If my Kuhmos are rated as 107 (and they are), then how is this dangerous? They were trying to sell me some Dunlops with a rating of 107 (because they incorrectly believe that the Kuhmos are 105). What am I missing here? Other threads here show evidence that VW themselves put 105 and 106 rated tires on V8s from the factory.

107 = 975kg (2149lbs.) - Kuhmo rating here: Kumho Tires Size Chart

[AndrieK]

AFAIK tyre manufacturers MUST specify the load rating on the tyre itself. Be careful with using data sheets off the net. It might be the latest and greatest info, but "Specifications might change without notice..."

Your tyres might be slightly different to this spec. I would assume your friends at Sam's Club might have read the load rating off the tyre...?

Either way, whether its 105 or 107 is academic. Both is ok. Just remember the pressures!!!

[gringoloco2000]

The load rating printed on the tire is 2149, so 107. I saw that when at Sam's, but did not know that it equaled 107 when they told me that it really meant 105. Bunch of BS. When I had the Conti tires they rotated/balanced and did a good job. I guess I will have to print out some stuff to get them to rotate balance again. I guess they need more training.