hyper inflation: let's cut to the chase

[AeroModder]

Got them checked out, and apparently I'm just being hypersensitive. The guy said that little bumps and ridges like that are normal, and it's just the belts stretching out. He equated them to a pregnant woman's stretch marks. He said if they get worse, come back and they'll check them out to make sure.

Though when I brought my car to the shop, it started stalling on me. I'm running some fuel system cleaner through the tank that removes water as well, and I'm pretty sure the water from the ethanol is going through. I'm going to be switching to non-blended gas, so I'll run the tank down as far as I dare.

[ShadeTreeMech]

Shucks when you mentioned bubbles I thought you meant ones you couldn't hardly miss! I've seen the ones you have before on all but the higer quality tires. Pefectly normal I'd say.

If the difference between the valley and peak were over 1/4" I'd worry a bit, otherwise drive happy.

PS nice job on the hi res pics. Could nearly count the molecules on the tread

[AeroModder]

It's a Canon 50D, 15.1 Megapixels. Photobucket resized them, though.

I found out my local tire shop has the Nokian Entyres available. After the Yokos wear out, I'll see if I can get a set of those in my size.

[2009Prius]

Does higher tire pressure really wear the suspension more?

[mcrews]

Any change to the desgin, layuot and geomerty of a car's suspension will increase wear on the weaker componets.
The suspension is designed with certain peramiters.
ie: A POT HOLE - The factory tire will absord a certain abount of the 'impact' given the reccomended inflation from the factory. Making the tire "harder" reduces the amount of impact that the tire will 'cushion'. Thus the next componet (bushings & shocks) absorb more than they are designed to normally absorb.

THis is very simpistic but........
If you drive older cars or tend to keep a car forever, this tends to matter over time.
I have 200,000 miles on my Infiniti Q45. And I drive about 40k a year. I plan to keep it another 100,000. I tend NOT to get over excited about pushing peramiters to the limit. I like to find a happy medium. When I am going on a trip longer than 100 miles, I will go to 47 (hot) psi. The rest of the time I stay at 38-41psi.

[CapriRacer]

Originally Posted by AeroModder

Some are inward, but there are a few outward ones:

http://i3.photobucket.com/albums/y93...ey/tire005.jpg

http://i3.photobucket.com/albums/y93...ey/tire006.jpg

After reading the link, these are definitely defective. The cords are very poorly lined.

As a generic term, these are called "undulations". They are caused by uneven spacing of the ply cords.

"Bulges" are wider than normal spacing - and the one in your photo is not too bad. Nothing to worry about.

"Indentations" are caused where the ply fabric overlaps during the manufacturing process. The tire is actually stronger there. You will always find one for every sidewall ply listed on the tire (perhaps 2!) In your photo, those are fairly normal. Nothing to worry about.

BTW Nitrogen behaves very much like air and increases pressure with increasing temperature just like air. In fact, there is very little advantage to using nitrogen:

Barry's Tire Tech

[slowmover]

My thinking is in line with what I have read CapriRacer post.

My experience, beyond personal, has been with big trucks where the dollars are huge (fleet) and one of the most often sighted supplier reps on the lot is the guy from the tire company. In example: a new front "steer" tire is holding a max rated 9,000-lbs. Each. Costing over $400. Each. Doesn't break in until past 35,000 miles, BUT, the truck will go through three/fours sets per year. Multiply that by dozens or even thousands of trucks.

Now, just down the road was a competitor who ran the same equipment and the same loads. But the tire pressures required were different. Same tire suppliers. Same rep, even. I did not run into anyone who could explain that satisfactorily. Big bucks, full-time accredited rep, a major line item on a fleet budget, etc, . . . .

Here is some info I pulled for some notes awhile back:

(Article) OVERDRIVE Magazine 12/2008

"Matching Tire Pressure to Load" (John Baxter)

The tire’s contact patch should be as large as possible while keeping a healthy amount of pressure and maintaining even contact between all the areas of the patch and the road. That means adjustment to reach “the optimal pressure for the load,” rather than inflating the tire to the same cold pressure all the time, says Doug Jones, customer engineering support manager at Michelin North America.

http://www.overdriveonline.com/match...ssure-to-load/

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(Article) BULK TRANSPORTER NEWS 9/2008

"Five tips to control your tire costs and improve vehicle performance, safety

With tires ranked as the second highest operating cost after fuel, a solid tire maintenance program can help reap solid dividends. Knowing the proper inflation level for your truck tires is crucial. TMC Recommended Practice (RP) 235 states the following determines the correct air pressure for a given load:

• Tire size and load rating
• Weight carried on each axle
• Number of tires on each axle
• Maximum speed the vehicle travels during its operation

http://bulktransporter.com/fleet/tru..._control_0908/

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(Website) Barry's Tire Tech

. . I hope you noticed how flat the wear index is for the radial tire. I interpret this to mean that conducting a "chalk test" is not a good way to determine what the best pressure is for wear.

http://www.barrystiretech.com/sae800087synopsis.html

(One of the screwups in the Ford Explorer/Firestone fiasco was that the tire pressure spec'd by Ford left no reserve. 20% is recommended.)


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(.pdf) FIRESTONE MEDIUM & LIGHT TRUCK DATA BOOK

(see pages 52 for truck fuel economy discussion; and page 64 (+/-) for load /pressure tables.) (Go to the man'f'r of your tires, download and copy).

http://www.trucktires.com/firestone/...ckDataBook.pdf



My personal experience is pretty simple: I don't want to upset the balance of ride and long life where the factory (since the era of radial tires pretty much) has established a guideline for empty and loaded conditions. Experimentation is limited, IMO, as long life and best braking/handling are paramount.

As with another post above I'm not so sure some of you guys understand that overinflation exacts a toll on the car that is, truly, unacceptable. Have you priced a front end rebuild? Is it understood that the entire structure is deleteriously affected, and that this takes place in every system? Your air-conditioning is leaking, and we have to remove the dashboard now?

Best handling, best braking, best tire life are probably within a very short range of what is recommended. I wouldn't go below the vehicle manufacturer recommendations (although the table allows it on mine, and, yes, I have tried it to no benefit), and going above it doesn't work so well either when load & pressure aren't a good match.

I've read/heard that 75% of sidewall maximum is a good place to start. Same with keeping rim width and tire tread width a match. It has worked for me on cars . . and until recently I have not ever been without a car at least twenty years old. And been the one to rebuild them. 200K on several of them as daily drivers. Where everything worked. I hate electrical reliability problems. Go ask a hardcore 4-wheeler about his trail rig. Or, why cop cars get retired with not so many miles. Vehicles taking hard hits to suspension, etc, wear out faster.

Even the best tires are cheap compared to suspension, steering, body bushings, unibody cracks, HVAC systems, electrical shorts and the rest that abused vehicles undergo.

So, the question is, how much money from marginally higher fuel mileage be needed for premature repairs? Permanently lessened reliability? I can't see a match, here. The cheapest car, the most economical car, is the one that lasts the longest for the least amount of money.

I shot a question or two to Barry of the Tire Tech site a few years ago and he was good to reply. I don't remember the entirety of it, but tire pressure and temperature relationships can be examined to dial in a combination past the Load Tables after a certain time/distance in steady-state driving. But, not much. You'll also need to put the car on a certified scale to find out weight per axle. And, if you're slick, use same to find weight per wheel. Published shipping weight is meaningless.

I regularly use an infrared laser thermometer on truck and trailer tires (as well as hubs and brakes) and I just look for consistency. Same with using a tread depth gauge. I rotate based on wear, mainly. I have handful of scale tickets showing the truck (and trailer) under a variety of loaded/unloaded conditions. The notes include various tire pressures.

On the current pickup it looks as though I'll be buying the second set of replacement tires at about a quarter-million miles. Stock size & brand. Factory pressures.

Where would increasing the pressure and upsetting an engineered "balance" benefit me?

.

[ShadeTreeMech]

Those were some very informative links, and give some definite food for thought. In summary, it would seem the recommendation for a passenger vehicle is 3-5 psi above the vehicle placard, not above the sidewall (except that 35 psi rated tires can go above)

In the case of my minivan that would put ideal psi around 40, which is 10 less than I thought was ideal. 40 psi also seemed the sweet spot on the charts, so assuming tire tech hasn't changed much in 30 years, that would be the ideal psi for my 2 ton minvan.

Thank you for a definitive answer to the question, and i apologize for any inflammatory threads I have posted. My life experience has lent a certain cynicism to too many things I fear.

[texanidiot25]

Originally Posted by sjr

Im wondering about the "donut spare" the small spare tires that say Dont go over 45 on the side and they are good for 60 PSI , has anyone ever ran a set of 4 of these and seem how they handle and what kind of gas mileage improvment they provide? I have 5 or 6 15" donut spares I would like to try out but would like to hear some real life experiance with them Scott

If you want to have a death wish, sure. Donuts are only made to be temporary tires, and go bald in a very short amount of time. Their tread design is really only good in dry weather. They are skinny as hell, and provide very little traction. Also their outer diameter tends to be much smaller than that of your car's normal tires (to fit in the trunk) and would cost you more in fuel due to effectively changing the final drive ratio, than they'd save you in fuel due to a lower rolling resistance. And, I'm going out on a limb here, but I believe the higher pressure is to help support the weight of the car on such a tiny tire.

There is a reason why the manufacturer prints on there about speed limitations as well as mileage limitations.

[slowmover]

I apologize for any inflammatory threads I have posted. My life experience has lent a certain cynicism to too many things I fear.

You only need read some of my threadkillers to know I'm the man in the mirror for that statement.


I suppose a more serious question has to do with internal tire temperatures. On another site I/we could find no information in re the point where delamination begins to occur (tire pressure monitors with a pre-set alarm of 157F). My pickup runs 127F externally when GVWR is close in hot Texas conditions.

In the same way here . . does anyone know risks in overinflation? Links? Anyone run an internal temp monitor and can recite differences in pressure vs temps? (Tire/wheel weight rating + actual weight on that pair; external factors, etc, etc).

.