Date: Sat, 29 Oct 2005 12:14:23 -0700
Reply-To: TJ Hannink <tjhannink@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: TJ Hannink <tjhannink@YAHOO.COM>
Subject: Re: Oh Boy! Tire Thread! (was RE: Michelin LTX/MS 215/75R15
tires...)
In-Reply-To: <014301c5dcab$fbbd4250$0a0ba8c0@RON>
Content-Type: text/plain; charset=iso-8859-1
The Bus Depot <vanagon@BUSDEPOT.COM> wrote:
We also know that U.S. D.O.T. safety requirements call for the tire to have a 6% safety margin above this if it is an LT rated tire. If it is a passenger car tire is must
first be de-rated by 9.09% (load capacity divided by 1.1) and then the 6%
margin applied to the resulting value. All this is as per government safety
guidelines, and is irrespective of tire size.
Can you provide a link to this particular (the 6% one) DOT safety requirement?
This is what I was able to find in Federal Regulations:
http://www.gpoaccess.gov/cfr/index.html
49 CFR--PART 571.110 (Amendment(s) published June 26, 2003, in 68 FR 38147)
Standard No. 110; Tire selection and rims for motor vehicles with a GVWR of 4,536 kilograms (10,000 pounds) or less.
S4.2.2 Tire load limits for multipurpose passenger vehicles, trucks, buses, and trailers.
S4.2.2.1 Except as provided in S4.2.2.2, the sum of the maximum load ratings of the tires fitted to an axle shall not be less than the GAWR of the axle system as specified on the vehicle's certification label required by 49 CFR part 567. If the certification label shows more than one GAWR for the axle system, the sum shall be not less than the GAWR corresponding to the size designation of the tires fitted to the axle.
S4.2.2.2 When passenger car (P-metric) tires are installed on an MPV, truck, bus, or trailer, each tire's load rating is reduced by dividing it by 1.10 before determining, under S4.2.2.1, the sum of the maximum load ratings of the tires fitted to an axle.
S4.2.2.3 (a) For vehicles equipped with P-metric tires, the vehicle normal load on the tire shall be no greater than the value of 94 percent of the derated load rating at the vehicle manufacturer's recommended cold inflation pressure for that tire.
(b) For vehicles equipped with LT tires, the vehicle normal load on the tire shall be no greater than 94 percent of the load rating at the vehicle manufacturer's recommended cold inflation pressure for that tire.
Note that Paragraph S4.2.2.3 refers to 'vehicle normal load' not 'vehicle maximum load' or GVWR.
Thanks,
TJ Hannink
Goldibox - 1987 Vanagon Camper, Wolfsburg Edition
1981 Bluebird Wanderlodge, FC-33
Winter Park, Florida
http://home.earthlink.net/~tjhannink/
http://groups.yahoo.com/group/wolfsburg_campers
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