Asking a Masters in Physics about tires is kind of like asking your Dentist about how to grow vegetables. They may or may not know much about it.

I don't hold Masters in Physics but I am a Chemist which is also little help in knowing tires. I have driven with BFG AT tires on three different vehicle for a total of over 300,000 miles. That amount of experience with them does leave me with a little knowledge of them. I have driven through rain, snow, ice, mud, rivers, sand, rocks, dirt, pavement and just about anything else that is out there to drive on. I can't say that I have driven in -25 temperature but not too far from it. My opinion is they are a very good overall tire. Not the greatest in mud but not bad and work very well in most other conditions. I have driven in snow 2 ft deep and had to stop because the bumper was throwing snow up on my windshield and I could not see.


I typically got around 70,000 miles out of each set and that is with considerable abuse. Any big tire is going to be heavy and unsprung weight is not as important as ground clearance when off-road. If you are drag racing you shouldn't have an off-road tire on the vehicle if you want to optimize traction. There are much better tires for that. I race a sports car in SCCA and unsprung weight is very important there. I run light weight slicks for that purpose. Each situation has an optimum tire. ATs are a compromise to try to be as good as possible in many conditions and they are pretty good at it.

When I bought my last set of tires, I considered the General AT2 tires but was not able to find them anywhere near me. I thought it was time to try something else and liked what I heard about them. What I didn't like was them not being available. I think they would be worth trying if they are available in your area.

 

i havent personally driven with BFG but i did buy the At2's for my truck but i got that stock size 255/70/16 i think not for certain and its snowing like crazy outside but i have went wheelin with my buddy who swears by BFG's and my tires hold their own against the BFGs thru mud snow and everything we drive on around here in the black hills i've drivin them about 10k so far and you cant even tell a hint of wear i dont really know when they are supposed to start showing but yeah just my 2cents

 

I have an engineering background... i remember the unsprung weight example in a class... but i did just type the words into google and found this:

I havent read through all of these, im at work, but.. these are some links with info about unsprung weight.

You can go to tirerack.com and just look up the BFG's vs the stock RT/S tires in the "specs" section to get the tire weight

Articles

Size Matters
http://www.wam.umd.edu/~greghess/sizematters.pdf

Finding Free Power
http://www.nerocam.com/SCC_TAPnew.asp

Bicycles and Unsprung Weight
http://web.archive.org/web/20031218...e/cornering.pdf

Fixing the 350Z: Why Lawyers Want Everyone to Run Staggered Setups
http://www.sportcompactcarweb.com/p...rt_2/index.html

Picking the Right Wheels For You
http://www.grmotorsports.com/wheels.html

Big Wheels, Big Trouble?
http://money.cnn.com/2004/12/15/pf/...day_big_wheels/

Wheel Weights Can Effect Your Vehicles Show and Go
http://www.tirerack.com/wheels/tech...eel_weights.jsp

Automobile Ride, Handling, and Suspension Design
http://www.rqriley.com/suspensn.htm

Threads

How much does wheel weight really matter?
http://corner-carvers.com/forums/sh...p?threadid=7019

Are 18" wheels and tires bling bling or a performance advantage?
http://corner-carvers.com/forums/sh...p?threadid=3661

How much will 17" wheels slow you down
http://web.archive.org/web/20050111...cgi/topic/7/303

Effect of Lighter Wheels?
http://web.archive.org/web/20050111...cgi/topic/7/301

Bigger Wheels and Tires?
http://web.archive.org/web/20040909...php/topic/7/863

Rotational Advice
http://forum.miata.net/vb/showthread.php?t=35522

If larger wheels are bad...why do sports cars have them?...
http://forum.miata.net/vb/showthread.php?t=40591

Wheel Weight, Who Cares?
http://forum.miata.net/vb/showthread.php?t=37803

1 Lb of unsprung weight =?? Static weight
http://forum.miata.net/vb/showthread.php?t=38135

Wheel Weights....Can They Make a Difference?
http://forum.miata.net/vb/showthread.php?t=40271

33.5 lbs/Corner Too Heavy??
http://forum.miata.net/vb/showthread.php?t=39256

Don't Small Wheels Mean Heavier Tires?
http://forum.miata.net/vb/showthread.php?t=38255

Whats With Huge Wheels?
http://forum.miata.net/vb/showthread.php?t=38033

18" Wheels too big? Take a Look!
http://forum.miata.net/vb/showthread.php?t=39868

I'm Finally Completely Convinced About Lighter Wheels and Tires
http://forum.miata.net/vb/showthread.php?t=35470

Do Wider Tires REALLY Provide More Traction?
http://forum.miata.net/vb/showthread.php?t=38946

Unsprung Weight 101
http://forum.miata.net/vb/showthread.php?t=34055

Unsprung Weight Effects Performance?
http://forum.miata.net/vb/showthread.php?t=34033

WO! The Joy of Lightweight Wheels!!!!
http://forum.miata.net/vb/showthread.php?t=35911

0-60 simplified wheel physics and garfield's wheel test
http://www.mini2.com/forum/showthre...d=279748&t=3730

Spreadsheet blows lid off lightweight wheel debate!!!
http://www.mini2.com/forum/showthre...&threadid=14738

Lightweight Wheels
http://www.mini2.com/forum/showthread.php?t=58149

In Defense of 17's
http://www.mini2.com/forum/showthread.php?t=10982

16 or 17 Inch Wheels?
http://www.mini2.com/forum/showthread.php?t=63449

18 or 19 Inch Wheels?
http://www.mini2.com/forum/showthread.php?t=81973

6tech Article
http://www.mazda6tech.com/index.php...id=16&Itemid=32

Wheel Weight and Performance

page 1 - page 2 - page 3

Some Wheel Weight Sites
http://www.wheelweights.net
http://www.wheelspecs.com

And yes i agree the BFG's worked really good off road, they just werent the right tire for me.

and to the guy who said the Mazda 4.0L must not be better than his 3.0L ... lol its fords 4.0L in my truck......

 

my friend had bfg's on his truck. after only 3 years and 30,000 miles, they started to dry rot. so, he went to Yokohama ATII's which don't look as agressive, but are better all around tire for on and off road.

 

You guess what??

 

Great, I have an engineering background too........civil engineering.....but by no means does it help my knowledge of tires!!! LMAO

Thanks for posting those links, I'll have to take a peek at them as I'm sure other will too.

And *I* was the guy that made the comment about your engine. It was said that way purposely. There are many 4.0L guys in here and I have never heard them say that BFG tires have caused them too loose significant HP and compare them to pulling a 600lb trailer. That's just crazy talk.

But once again, thank you for the links.

 

Ummmmm...ok. I would have to disagree with that, considering unsprung and sprung weight and rotational weight has everything to do with physics. Read up on some of the links that roddy here has provided. Granted, more then half don't work, I managed to find one that I believe proves him wrong.



I appreciate all the links man, but like I said before...more then half of them didn't work. Who knows, maybe I need to be a member to access them or something, but most of them came up as a "error" page.

However, I managed to get this one to work, and found it very interesting.

http://forum.miata.net/vb/showthread...2&page=2&pp=25

Check out the second page...post 31 by Lance Schall. He lays it out pretty straight forward with a basic equation that can deal with increased unsprung weight through heavier tires or wheels. If you want, you can plug your numbers from your original post in there.

Increase in tire weight = 17 pounds
Of course, 4 wheels
And his calculations about momentum due to rotational rotational mass is 1.5 times that of the weight increase.

Plug them in...17 x 4 x 1.5 = NOT 680 pounds... 102 pounds. So, "thats like pulling a 102 pound trailer"

With that being said, hopefully you didn't think I was disagreeing with you about the fact that it does take more energy to accelerate and stop a heavier tire. Thats just common sense. I just didn't think that an increase of 17 pounds per tire is equivalent to pulling a 680 pound trailer.

I of course am not an engineer, and I don't have a masters in Physics. But I did take a few Physics courses when it was my major for about 3 years. But I believe I understand all this right...however it has been a few years since i've focused on anything like this.

 

That 102lbs makes more sense. I just rotated my tires this afternoon and they might each weigh 60lbs , that's rim/air/tire. So just the tires them self would be around that 100lb ball park.

I also took the 4 sand bags out of the box and at 30kg's a piece, they are around what the wheels weigh.

 

102lbs, i guess i am wrong. Ill have to look into it again when i have some free time

Edit* ok broke out a text book!

-" its said that 1lb of rotating mass is equal to 10lbs of dead weight"

Now rotational and unsprung weight are different things.... but this is where the 680lb calculation came in... 17x10x4 = 680

lol, anyway, im gonna leave it here. You guys can google this stuff, its kinda fun to learn, there is also a Horsepower formula tied to this.

 

Roddy, Wyldechild has a fu*cking hard on for his *** friend that "dosent have his masters" yet.

It sounds like you have a pretty good grasp on what you are talking about and James you do as well.

The bottom line is that BFG is a great tire. Maybe not the best in alot of peoples opinon but then again ALOT of people swear by them and think they are the best.

Do your research and get the tire that fits your needs and your budget. There is no point in getting the BFG's because they are "the god" of tires... There are othere meats out there that will performe just about as well for less money.

 

Close enough to a masters Jake...1 semester of lab work, with all of his classes finished, is pretty much a Masters. Regardless, 5.5 years for a masters in Physics with a concentration in both mechanical and electrical engineering from one of the top engineering schools in the nation is pretty impressive. I have no "hard on," I just like to believe what he says when it comes to physics. The reason I referred to him is because I don't know enough about it to have a really valid argument.

And you're right, most people don't push their rigs hard enough, or pay attention enough to notice a difference between a few different all terrain tires. I guarantee the AT2's, Nittos and BFG's would all do what you needed them to do just about the same.

 

Very well said kid.

I would bet the Bridgestone Dulers would be a great tire as well as a few of the Mastercraft and Cooper AT's.

 

The biggest problem with choosing tires, is the LACK OF information available. Ofcourse each manafactuer is going to say their tire is equivelant to gods gift to the world, however user opinions and reveiws of different tires in different situations is most valuable.

My advice to the OP is to plug both into google with a few different keywords to see what you come up with.

Also, fall of 07, I drove my truck thruogh a small mud pond, that was about 2ft deep of water. about 5ft acrossed, in the middle of a house development... to my shear surprise I did not get stuck, even after traversing it about 50x.