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Old 11-02-2011, 11:50 PM
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Overinflating tires..good Idea or bad Idea?

I tried doing a search on this but didn't find anything. I wanted to know how safe is this. I was doing some research over the Internet on overinflating tires to get better MPG's and better handling, some say it's good some say it's bad. The bad things I heard about it was that overinflating tires makes the tire narrower on the road surface, thus less traction. The Jeep calls for 33 psi on all tires, I upped to 35 psi. Should I be concerned that if the air of the tired get hot from driving or weather and it expands, that the tires will burst? So far, I feel that the tires are harder and at one instance I was making a sharp turn and it felt that the Jeep slipped from underneath me, but then again that could have been the left over snow from the other day. Should I take them back down to 33psi?
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Old 11-03-2011, 12:05 AM
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Re: Overinflating tires..good Idea or bad Idea?

Yes.......
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Old 11-03-2011, 12:27 AM
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Re: Overinflating tires..good Idea or bad Idea?

bad idea
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Old 11-03-2011, 09:37 AM
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Re: Overinflating tires..good Idea or bad Idea?

you should not over inflate passed the maximum inflation on the tire itself.
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Old 11-03-2011, 10:04 AM
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Re: Overinflating tires..good Idea or bad Idea?

Quote:
Originally Posted by Blueflame1979 View Post
I tried doing a search on this but didn't find anything. I wanted to know how safe is this. I was doing some research over the Internet on overinflating tires to get better MPG's and better handling, some say it's good some say it's bad. The bad things I heard about it was that overinflating tires makes the tire narrower on the road surface, thus less traction. The Jeep calls for 33 psi on all tires, I upped to 35 psi. Should I be concerned that if the air of the tired get hot from driving or weather and it expands, that the tires will burst? So far, I feel that the tires are harder and at one instance I was making a sharp turn and it felt that the Jeep slipped from underneath me, but then again that could have been the left over snow from the other day. Should I take them back down to 33psi?

Reread your original post. Overinflating your tires means less rubber on the pavement - that means WORSE handling. Bad idea. Especially on wet, snowy, or icy roads.
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Old 11-03-2011, 10:33 AM
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Re: Overinflating tires..good Idea or bad Idea?

Letís put this into numbers. The jeep weighs 4000 lbs. Each tire is supporting 1000 lbs. At 33 psi, each tireís contact patch would be 1000 lbs ł33 lbs/in2 = 30.3 square inches. I donít know what the tread width is, but in any case it wonít change. Letís say itís 9 inches wide. So to find out the length of tread on the road it would be 30.3 in2 ł 9 in = 3.36 inches. That means that at the recommended pressure each tire has a strip of tread 3.36 inches long in contact with the road. This is what the engineers designed for with the stock setup. So this is the best compromise of efficiency and handling.
Long story short, at 35 psi, the strip would be 3.17 inches long. The rolling efficiency might be better but cornering and braking would be worse.
IIRC the max tire pressure is 45 psi. At that pressure you would only have 2.5 inches of tread length contacting the road. Cornering and braking would be really bad and you would be risking a blowout if you ran over something sharp.
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Old 11-03-2011, 12:07 PM
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Re: Overinflating tires..good Idea or bad Idea?

Quote:
Originally Posted by Archer9 View Post
Letís put this into numbers. The jeep weighs 4000 lbs. Each tire is supporting 1000 lbs. At 33 psi, each tireís contact patch would be 1000 lbs ł33 lbs/in2 = 30.3 square inches. I donít know what the tread width is, but in any case it wonít change. Letís say itís 9 inches wide. So to find out the length of tread on the road it would be 30.3 in2 ł 9 in = 3.36 inches. That means that at the recommended pressure each tire has a strip of tread 3.36 inches long in contact with the road. This is what the engineers designed for with the stock setup. So this is the best compromise of efficiency and handling.
Long story short, at 35 psi, the strip would be 3.17 inches long. The rolling efficiency might be better but cornering and braking would be worse.
IIRC the max tire pressure is 45 psi. At that pressure you would only have 2.5 inches of tread length contacting the road. Cornering and braking would be really bad and you would be risking a blowout if you ran over something sharp.
yeah, what he said...
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Old 11-03-2011, 03:07 PM
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Re: Overinflating tires..good Idea or bad Idea?

sounds like you are a math professor or a nerd either way great explanation
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Old 11-03-2011, 03:28 PM
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Re: Overinflating tires..good Idea or bad Idea?

Quote:
Originally Posted by Archer9 View Post
Letís put this into numbers. The jeep weighs 4000 lbs. Each tire is supporting 1000 lbs. At 33 psi, each tireís contact patch would be 1000 lbs ł33 lbs/in2 = 30.3 square inches. I donít know what the tread width is, but in any case it wonít change. Letís say itís 9 inches wide. So to find out the length of tread on the road it would be 30.3 in2 ł 9 in = 3.36 inches. That means that at the recommended pressure each tire has a strip of tread 3.36 inches long in contact with the road. This is what the engineers designed for with the stock setup. So this is the best compromise of efficiency and handling.
Long story short, at 35 psi, the strip would be 3.17 inches long. The rolling efficiency might be better but cornering and braking would be worse.
IIRC the max tire pressure is 45 psi. At that pressure you would only have 2.5 inches of tread length contacting the road. Cornering and braking would be really bad and you would be risking a blowout if you ran over something sharp.
You see, Now that's what I call a freaking explanation! I mean no offense to every body else that gave their advice, but it's always good to know why things are good as they are and why they can go bad. Now I can get technical on another Noob. But either way, you guys always pull through and I would be wrong to not consult with everyone here, before putting my Jeep in Danger.
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Old 11-03-2011, 03:36 PM
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Re: Overinflating tires..good Idea or bad Idea?

Quote:
Originally Posted by king View Post
yeah, what he said...

That's funny cause I almost said the same exact thing.
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Old 11-03-2011, 06:27 PM
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Wink Re: Overinflating tires..good Idea or bad Idea?

Hahahah. Thanks guys! I'm no professor and I don't think I'm a nerd (although I have nothing against nerds). I started in cartography 30 years ago and we had to use spherical trig in those days to calculate great circle distances etc. Couldn't do it today to save my life, but I like using math to try to solve problems when I can. I started thinking about this when there was another thread about airing down for the trail or beach.

There are lots of physics students here....I actually thought someone brighter than me would find a mistake with my numbers....
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Old 11-03-2011, 08:22 PM
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Re: Overinflating tires..good Idea or bad Idea?

I'd be more concerned with getting an accurate tire gauge. You might think you're running 33 or 35 and actually be running significantly more or less because so many gauges suck. I'd say instead of worrying about 2 psi, invest in a good analog gauge if you don't already have one.
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