Inflation - too much too little or is it all bs

[BajaSportsmobile]

I hope you are using at minimum a 78 percent Nitrogen mixture in your calculations, for liability reasons alone. It is rocket science after all.

[edroid]

Originally Posted by BajaSportsmobile

I hope you are using at minimum a 78 percent Nitrogen mixture in your calculations, for liability reasons alone. It is rocket science after all.

I bet if the space shuttle had tires, there would be thousands of forum pages with the "rocket scientists" arguing about optimal pressure for smooth ride, mpg of rocket fuel, and trajectory!

[rob_gendreau]

Originally Posted by vlamgat

Michelin has a video on Youtube that is quite specific in advising that upon the blow out, you floor the gas and then slowly lift off. You do not take your foot off the gas and absolutely do not hit the brakes.

I don't want to nick pick, but it is sorta important. What they recommend is that you stay on the gas; "flooring it" is not what they say, for good reason. I realize that flooring our vans doesn't exactly pin you to the seat, but that BMW in the video would probably react unpleasantly to that input. The idea is to not to do anything to unsettle the vehicle. It's very much like dropping two off on the track.

And speaking of the track, that IS one place where you do work with hot tire pressures, not cold (at least once you start lapping). The rule of thumb we used is about 1 psi increase for every 10 deg F the ambient temperature rises (have never seen the 2 degree figure). But even within the relatively controlled environment of a track there are things like track temp, and whether you parked with one side in the sun, etc. You DO notice a difference, especially at a place like Thunderhill in August. Gets REALLY greasy in the PM. And sun in Tucson on your tires can make a big difference from say a 68 degree AM to a 108 degree PM, but generally it's taken into account by the manufacturer and unless you're seeking the ultimate in performance you default back to a recommended cold temp to start.

And for max perfomance you have to look at the temp of the tire itself, not just the air within. It's like a more specific version of the chalk test. You'll see dudes with their pyrometers sticking tires like crazed accupuncturists.

And if you want to see what truckers do, there are calculators online. Here's one example: http://www.yokohamatire.com/air_pressure_calculator

[rob_gendreau]

I had emailed both BFG and TireRack about the inflation tables for BFG A/T K/Os.

Here's what BFG said:

In regards to the email you sent stating:
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I cannot find a load inflation table for my BFG AT K/O tires, put on my vehicle as replacements for a somewhat smaller tire. Where can I find them? Or can I use a generic table for inflation for the same sized and load-rated tire?

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You can go to Tirerack.com or call us at the number listed below with the size tire and we can give it to you over the phone.

I had sent one to TireRack saying I had a modified van; here's what they said:

Typically that type of 3/4 ton chassis will require 10 ply tires with an inflation pressure of 65-80psi, however you will likely not find any inflation tables for modified vehicles.

We had a misunderstanding about "modified." I tried to clarify with them that I meant the GVWR was the same, just upsized rims and tires. But they still haven't gotten back to me.

Seems like they don't wanna commit. Odd since every other manufacturer seems to provide this info as others have noted. Makes me think that although I like these tires, maybe another brand is in order next time.

[ANZAC]

Someone find me a table where a different brand lists a different load for a given size/pressure.
It doesn't exist. So if BFG hasn't bothered to publish it, use someone else's.

All the tables are based on what the Tire and Rim Association publishes. As long as you haven't exceeded the maximum load for your brand/model of tire, just pick the right pressure for your new size based on the example I laid out in the other thread. It isn't that complicated.
http://sportsmobileforum.com/viewtopic. ... 2&start=22

I have BFGs.

[rob_gendreau]

I even mentioned that manual when I emailed them, figuring they'd just say "follow that." I am, of course, but it's like I'm spying on them or something. Geez.