erikiksaz1

My local tire guy told me that filling up to the maximum psi has a few advantages:

1) longer tread life. The middle of the tire takes much longer to wear than the shoulders.

2) smaller chance of forming a bubble. When hitting a pothole, the tire with low pressure will cave in, creating uneven spots of excess pressure. Weak spots (i suppose the sidewall), will bubble.

3) greater chance of deflecting nails. The tires have a tendency to run over a nail, instead of run over and around it.

Now, he's been in the business since the 70s, so I figure he's learned quite a few things.

But here's my problem. I've been running my new 512's at about 50 (51psi max), and they feel like balloons! The car sticks, but it feels floaty. Could this be due to the tires being new? I've only put about 100 on em so far.

tjbizzo

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by erikiksaz1 &raquo;</TD></TR><TR><TD CLASS="quote">But here's my problem. I've been running my new 512's at about 50 (51psi max), and they feel like balloons! The car sticks, but it feels floaty. Could this be due to the tires being new? I've only put about 100 on em so far.
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Personally I wouldn't run them that high, maybe about 35-38 psi. If your car feels floaty then it's probably either something wrong with the car (shocks, suspension bushings, etc) or the fact that these are more of an all season tire than a really high performance tire. btw I have them on my CRX and they don't feel at all floaty to me.

potatostix

That sounds retarded to me. Just because a tire lists its max inflation perssure, doesnt mean thats where it should be. Over inflating a tire will cause it to wear prematurely in the center of the tread. Only thing that would really be a plus is you might get better gas mileage.

Neo79Si

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by erikiksaz1 &raquo;</TD></TR><TR><TD CLASS="quote">My local tire guy told me that filling up to the maximum psi has a few advantages </TD></TR></TABLE>

Whether he's been in business for years or not...the only problem with your tire guy's advice is that it's mostly anecdotal...meaning, based on feedback he's heard from customers. There's no real science or logic behind it.

I would NOT recommend using the max inflation stamped onto the sidewall. Coming from a tire engineer, here is my perspective on the advice you were given...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by erikiksaz1 &raquo;</TD></TR><TR><TD CLASS="quote">
1) longer tread life. The middle of the tire takes much longer to wear than the shoulders.

2) smaller chance of forming a bubble. When hitting a pothole, the tire with low pressure will cave in, creating uneven spots of excess pressure. Weak spots (i suppose the sidewall), will bubble.

3) greater chance of deflecting nails. The tires have a tendency to run over a nail, instead of run over and around it. </TD></TR></TABLE>

1] False - a properly aligned car should wear tires evening. The real problem is...this is why your car feels "floaty". Think about it...you effectively just reduced the amount of contact with the road because now the shoulders are not engaged as much as they once were. You aren't able to generate as much cornering force as when the tire is properly inflated.

2] False - increasing the inflation that much will reduce the amount of deflection the tire goes through over bumps/potholes. That means, a tire cannot "give" as much as when properly inflated.

3] Can't be sure - there's no way to really prove this

IMO - your car feels floaty because your contact patch has shrunk, and you run a greater risk of damaging a wheel/tire at this inflation than whatever pressure is set by the vehicle manufacturer. Here is a quote from the Tire Rack's "tire tech" section to back me up...

Correctly inflated tires receive appropriate support from the contained air pressure to provide an even distribution of load across the footprint and help stabilize the tire's structure. And while most drivers recognize that this has a significant impact on tire wear, rolling resistance and durability, only a few realize underinflation also has a noticeable influence on how quickly and precisely the tires respond to the driver's input.

http://www.tirerack.com/tires/...hid=2

When a tire is designed, we use a pressure representative of the load range of that tire. We optimize all the performance characteristics of that tire for that inflation range. Once you inflate to max inflation, but you aren't @ max load conditions, you've pretty much un-done all the work the engineers have done for you.

Let me know if you have more questions

Matt

Mike_C

that is just silly. drop those bastards like they're hot. i once had "a guy in the business for twenty years" tell me that there is no such thing as a 205/50/15 tire. i even had to explain to him what each number meant... he was used to truck tires. astounding considering he owned a tire shop... i wonder how he figured out what to put on cars all this time.

erikiksaz1

Very informative, thank you all

crucian

When a car is rolling the tires heat up from friction and road heat. When anything heats up, it tends to expand. The PSI in you tire will rise as the temperature rises. If you inflate your tire to max PSI, what do you think will happen when your tire heats up?