Community Forums

Bigdaddy · 01-31-2011, 09:27 AM

I have asked this question at our bus shop. Why does the wt. rating for single tires more than the dual rating? No answers! I know we have some tire experts here.

Wayne M · 01-31-2011, 09:33 AM

See if this helps: Tire Rack Information

GaryKD · 01-31-2011, 09:49 AM

Hi Bigdaddy,
In addition to what Wayne M posted, the more immediate factor on a daily bases is weight shift. As we motor down the road, the weight in the coach will shift depending on what is happening to the coach. Because the rear axle carries much more weight than the front axle, the weight shift, while temporary, can be dramatic. The reduced load rating helps provide the reserve capacity to endure the constant weight shifting.

motohomer · 01-31-2011, 04:04 PM

Good Question.

Bridgestone Commercial Truck Tires

The main reason that dual tire load limits are set at a lower rating than single tires is that tires paired up as duals do not always contact the road surface equally. Examples of this would be ruts in the road surface, climbing over curbs, mismatches in inflation pressure and/or remaining tread depth, to name a few.
This unequal road surface contact results in one of the dual tires ending up carrying more than its fair share of the load. In order to provide a “safety cushion” for when this happens, the maximum weight allowed is set lower than for a single application.

DriVer · 01-31-2011, 10:13 PM

My position is basically detailed in Wayne M's post.

I am expecting that the proximity of the tires to one another in a dual configuration (rubbing) plus the heat that is generated between the tires may have set the load number lower per tire in a dual application. This is what I understand may be one of the reason why this is so.

About dissimilar inflation, I got around that with a Crossfire.

powerboatr · 01-31-2011, 10:20 PM

Quote:

Originally Posted by Wayne M

See if this helps: Tire Rack Information

x3

Midniteoyl · 02-01-2011, 01:26 AM

Main reasons:

- Accounts for differences in tire height, and thus loading

- Compensates for uneven loading caused by road crown

- Lessens the chance of the tires rubbing if under inflated/overloaded

Not so much a reason:

- "If one tire goes flat, theres a 'reserve' for the other 3". The amount of under rating doesnt allow for much more than 'get off the road NOW'.

DriVer · 02-01-2011, 10:03 AM

Quote:

Originally Posted by Midniteoyl

Not so much a reason:

- "If one tire goes flat, theres a 'reserve' for the other 3". The amount of under rating doesn't allow for much more than 'get off the road NOW'.

I agree, In no way shape or manner is that any type of reason. A flat tire on a rear dually axle is a disaster because it would be imminent that the 2nd tire will blow in relatively short order since it would be grossly overloaded.