an E rated tire NEEDS to be more highly inflated at all times than does a D rated tire.
You might be right but you have offered no evidence to support your case other than hyperbole in your long-winded treatise above.
Who is Discount? Where did these charts originate? Who wrote them? These are for determining what pressure to run in new tires based on the ratings of the original ones and their recommended inflation pressures. What were your original tires? What was their load range? What was their service description? What was their original recommended inflation pressure? Have the charts you posted been verified by your tire manufacturer? or by uhm, anyone?
Blah, blah, blah. Discount? You might know them as America's Tire but according to them, they are the world's largest tire and wheel retailer. I don't know if that's true or not and I don't care who wrote their load index charts. I suspect it was a tire engineer and the company stands behind their recommendations.
Did you consult these charts before deciding on replacement tires? They seem a poor match based on the information you've shared. So the front tires should be below 35 psi according to your charts and the rears should be between 35 and 40 psi. That all seems too low and like you've got too much tire for your load. Not saying you'll have problems but wow that seems like a serious component mis-match and proves my case than an E rated tire isn't necessarily necessary and I bet you're WAY below the load ratings for your tires if you're within Ford's gvwr and gawr's.
You calculated what each pound of pressure is capable of supporting in your tire, which is erroneous because there is an absolute minimum, then assumed a 50/50 weight distribution, which is erroneous unless you've measure your van to have such which is very unlikely for the former and unproven for the latter, and used the same pressure front and rear which matches that last mistake but in reality creates one of its own, then used a safety factor smaller than your overall change, which is a false equivocation. The answer might be right (too many assumptions to know) but the formula sure isn't.
Here's the actual load on my rig with 46 gal of diesel and water tank and jugs topped off. For a trip the additional weight might be 400 pounds. Weights were measured at the truck scales at the Bellmont truck stop on I40 outside of Flagstaff. I can scan the receipt if you would like verification.
Front axel 4660 lb
Rear axle 5240 lb
Gross weight 9900 lb
I believe I have done my homework. I'll continue to run the 315 Duratracs rated for a max psi of 65 at 45 in the front and 50 in the rear based on my axel weights. While you provide some interesting information regarding the differences between D and E rated tires you don't back it up with any studies other than your opinions and a chart from Toyo. I'll stick with the E-rated tires for my application thank you.
spouting off things like "Duratracs are rated at xx psi and xxxx pounds" without application or sizing data is not only unhelpful but could be dangerous should someone take your "information" and use it in the real world.
Thanks for the tip.:bowdown: Last time I checked this was a forum for 2 and 4wd camper vans. I hope someone can find my information useful and decide for themselves. That is, afterall, what discussion forums are about: providing stoke and information.
