Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×
 


Reply
 
Thread Tools Display Modes
 
Old 10-17-2009, 06:25 PM   #21
Senior Member
 
Join Date: Feb 2009
Location: Seattle
Posts: 172
Re: E series tires

Well, I have to report that my new (about 2,000 miles) 285/75/16 "E" rated BFG AT's are pretty scary on wet roads, and in the Pacific N-West, we own the book on Wet Roads. Coming across Snoqualmie Pass today, riding into the teeth of the first Pineapple Express of the season was pretty spooky. I don't remember The Van being so loosey goosey with the "D" rated tires. I have them aired up to the recommended 80 in the back and 60 in the front, sort of like ice racing on Lake Erie.

I'll be driving slow and in the right lane between October and May...

Tom
__________________

__________________
2005 SMB RB 50 4X4 w/ a 6.0 PSD
flyfisher is offline   Reply With Quote
Old 10-17-2009, 06:42 PM   #22
Senior Member
 
Join Date: Jul 2008
Posts: 496
Re: E series tires

Flyfisher, you might have too much air for the wet roads. 80 psi is MAX.
__________________

j.whitbread is offline   Reply With Quote
Old 10-17-2009, 07:22 PM   #23
Senior Member
 
Join Date: Feb 2009
Location: Seattle
Posts: 172
Re: E series tires

j. whitbread, I'm going to reduce the pressure, just to get a little more contact with the road. A 9,200 lb Van on a "plane" wouldn't be a pretty sight.

Tom
__________________
2005 SMB RB 50 4X4 w/ a 6.0 PSD
flyfisher is offline   Reply With Quote
Old 10-17-2009, 07:25 PM   #24
Senior Member
 
Join Date: Jul 2008
Posts: 496
Re: E series tires

I have mine between 50-55.
j.whitbread is offline   Reply With Quote
Old 10-18-2009, 11:28 AM   #25
Site Team
 
Ford_6L_E350's Avatar
 
Join Date: May 2007
Location: Washington - Ridgefield
Posts: 4,727
Re: E series tires

A diesel van weighs more, so I have mine at 65psi front and rear. We could give you better guidance if you fill in your signature so we know what van, engine, options you have.

Mike
__________________
Alaska to Key West, Labrador and more
Prostate cancer survivor. See Thread Prostate cancer and Sportsmobiles
2015 VW GTI 2020 Fiat 124 Spider
2012 E250 Hitop camper
Ford_6L_E350 is offline   Reply With Quote
Old 10-19-2009, 09:13 AM   #26
Senior Member
 
Join Date: Feb 2009
Location: Seattle
Posts: 172
Re: E series tires

Quote:
Originally Posted by Ford_6L_E350
A diesel van weighs more, so I have mine at 65psi front and rear. We could give you better guidance if you fill in your signature so we know what van, engine, options you have.

Mike
Thanks Mike, I have a 2005 SMB RB50 with the 6.0 PSD (lot's of initials here)
__________________
2005 SMB RB 50 4X4 w/ a 6.0 PSD
flyfisher is offline   Reply With Quote
Old 10-19-2009, 09:35 AM   #27
Site Team
 
Ford_6L_E350's Avatar
 
Join Date: May 2007
Location: Washington - Ridgefield
Posts: 4,727
Re: E series tires

Based on the weights of other similar SMBs, you probably should be running 65 psi front and 55-60 psi rear. You really need to weigh the van (fully loaded) to get a more accurate idea.

Mike
__________________
Alaska to Key West, Labrador and more
Prostate cancer survivor. See Thread Prostate cancer and Sportsmobiles
2015 VW GTI 2020 Fiat 124 Spider
2012 E250 Hitop camper
Ford_6L_E350 is offline   Reply With Quote
Old 10-19-2009, 09:50 AM   #28
Senior Member
 
Join Date: Feb 2009
Location: Seattle
Posts: 172
Re: E series tires

Mike, The Van weighs 9,220 lbs, with me, and full water, fuel and propane tanks.

Tom
__________________
2005 SMB RB 50 4X4 w/ a 6.0 PSD
flyfisher is offline   Reply With Quote
Old 10-19-2009, 12:00 PM   #29
Site Team
 
Ford_6L_E350's Avatar
 
Join Date: May 2007
Location: Washington - Ridgefield
Posts: 4,727
Re: E series tires

The best method to calculate tire pressure requires weight measurements for the front and rear of the van, even better is each individual tire weight measurement. Then calculate how much pressure you should be running. This from an earlier thread:

Old school answer:

The pressure rise from cold tire to hot tire should be 4-6psi. Less than 4psi rise means the cold pressure is too high, more pressure rise means the cold pressure is too low.

Best answer:

Get the actual weights on the tires and ask the manufacturer for the proper pressure for that weight.

My method:

Again, get the actual weight. Compare it to the max weight on the tire. Do some math.


Actual weight/Max weight X Max Pressure = Desired pressure

If you have 2500# on a tire rated at 3000#@80psi you get:

2500/3000 = .8333 .8333 x 80psi 66.66psi, which I round up to 70psi


Then I always round the pressure up. Much better to err on the side of too much pressure than on the side of too little pressure.

As a general rule, D and E rated tires carry the same load at the same pressure. The big difference is E rated tires can handle more pressure, hence more load.

My van weighs in at 9800#, fairly evenly split front/rear side/side. The tires are LT275/70-18E rated at 3640# @ 80psi. For 4 tires, that would add up to 14,560# at 80 psi. My math says I have 9800/14560 of full load. That is about 67% of the max tire ratings. 67% of 80psi is about 55psi. I run 65 psi. A good safety margin. I will never run a tire at its full capacity. Just too much at stake for me.

4 tires rated at 3000# would be too close for me. Going down the road with some lean to the road, the outside tires could be overloaded for many miles. I wouldn't do it. I always want at least a 10% safety factor, 20% is better. Hence, my 65psi in my tires.

I always round up with tire pressures since higher pressures (within the max tire ratings) will reduce tire temps and might tend to wear the center of the tread. Lower tire pressures will cause higher tire temps and can easily cause a tire to fail.

Your RB probably has less weight on the rear than our EB does, hence lower tire pressure on your rear tires.

There should be enough here to confuse the issue. Good luck.

Mike
__________________
Alaska to Key West, Labrador and more
Prostate cancer survivor. See Thread Prostate cancer and Sportsmobiles
2015 VW GTI 2020 Fiat 124 Spider
2012 E250 Hitop camper
Ford_6L_E350 is offline   Reply With Quote
Old 10-19-2009, 12:18 PM   #30
Senior Member
 
Join Date: Feb 2009
Location: Seattle
Posts: 172
Re: E series tires

Great information, thanks Mike!
__________________

__________________
2005 SMB RB 50 4X4 w/ a 6.0 PSD
flyfisher is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Sportsmobile SIP or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 03:22 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
×