Pre-Chase Tip: Check those tires

[Jason Foster]

Just a quick reminder to check those tires for the correct pressure. As temperature changes and atmospheric pressure changes, tires can become deflated, and that can affect gas mileage and driving safety.

Also, don't forget to check that spare tire. Make sure it is in good condition and is also inflated to the correct pressure.

Don't use the pressure listed on the tire, always go by the air pressure listed in the owner's manual, or on the label which is often in the door sill area on the driver's side.

I'll post more suggestions later (in different threads), to help remind folks to get ready for the chase season.

 

[Steve Worthington]

Just a quick reminder to check those tires for the correct pressure. As temperature changes and atmospheric pressure changes, tires can become deflated, and that can affect gas mileage and driving safety.

Also, don't forget to check that spare tire. Make sure it is in good condition and is also inflated to the correct pressure.

Don't use the pressure listed on the tire, always go by the air pressure listed in the owner's manual, or on the label which is often in the door sill area on the driver's side.

I'll post more suggestions later (in different threads), to help remind folks to get ready for the chase season.

ummmmm, "Don't use the pressure listed on the tire" are you kidding???? The pressure listed on the tire is what YOU SHOULD GO BY. The tire company knows what their tire is rated at, not the car manufacture.

 

[Steve Polley]

ummmmm, "Don't use the pressure listed on the tire" are you kidding???? The pressure listed on the tire is what YOU SHOULD GO BY. The tire company knows what their tire is rated at, not the car manufacture.

Actually this is very incorrect. You should ALWAYS use the vehicles recommended inflation pressures. The pressure on the tires is only the maximum COLD psi recommended for that tire. The gross weight of the vehicle greatly effects how much air is needed in the tires. Too much air in the tires is just as bad as not enough. I teach this daily to my students as well. If the tires are not inflated per the vehicles specs, tire wear and pulling issues will develop as the tire is not having the proper contact with the pavement. Here is a link with more info also.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=8

 

[Greg Campbell]

The value on the tire is most always the _maximum_ safe cold inflation pressure. Even this number includes a huge safety factor, probably 2x if not more.

That's not to say that running 5 PSI over the owner's manual / door label suggestion is a bad thing! You'll gain fractionally higher gas mileage, possibly better tire wear and, most importantly, you'll increase the tire's resistance to hydroplaning. The improvement isn't dramatic, but it just might be enough to save you from a wreck!

Keep in mind that the manufacturer's suggested pressure is a compromise between the engineers, who may well request higher values, and the sales people, who want 'luxurious' ride quality. The number is not written in blood!

My car's suggested PSI is actually too low. I get uneven tire wear at the 'book' 32psi. 36~37 is _required_ to eliminate worn edges. FWIW, I've been running right around 40 at both ends for the last few years with zero side effects except a slightly bumpier ride. There's also a marked improvement in 'feel' when driving anywhere near the edge of traction. Beyond 40 the ride quickly becomes intolerably rough.

As always, "Your mileage may vary," but it might be worth playing with your pressures.

 

[Adam Wolff]

Actually this is very incorrect. You should ALWAYS use the vehicles recommended inflation pressures. The pressure on the tires is only the maximum COLD psi recommended for that tire. The gross weight of the vehicle greatly effects how much air is needed in the tires. Too much air in the tires is just as bad as not enough. I teach this daily to my students as well. If the tires are not inflated per the vehicles specs, tire wear and pulling issues will develop as the tire is not having the proper contact with the pavement. Here is a link with more info also.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=8

This is excellent advise for most drivers. However, I do disagree with the statement "You should ALWAYS use the vehicles recommended inflation pressures.". This is correct when using like or similar tires that came with vehicle. Tire types and sizes will change the tire footprint at those recommended tire pressures. One should check the tire "footprint" and correct the pressure accordingly. Examples would be stiffer sidewalls in performance and mud tires which would require less psi to correct the tire footprint. I know, I know, I'm picky I mention this because I know there are members running A/T's and M/T's.

 

[Ben Holcomb]

This also makes the president happy, as inflating tires was part of his energy policy during his campaign in 2008.

 

[Rob Wadsworth]

I'm sure that most know that the reason that car mfrs have their own tire pressure recommendations. It is there because of the bias of vehicle weight distribution. Front tire pressure is usually higher in front wheel drive vehicles - due to the fact that the tire 'footprint' will spread out as weight increases and more air pressure is required to maintain a uniform pattern on the road surface. Rear tires have less air pressure in fwd cars for the same reason. The vehicle will both break and handle with better consistency and predictability with a consistent footprint on the road surface when one follows the mfrs suggested tire pressure for your particular vehicle.

Either way, it is important that one keeps all of the ducks in a row when facing adverse driving conditions during the upcoming chase season. Thanks for the tip and heads up!

 

[Steve Worthington]

Actually this is very incorrect. You should ALWAYS use the vehicles recommended inflation pressures. The pressure on the tires is only the maximum COLD psi recommended for that tire. The gross weight of the vehicle greatly effects how much air is needed in the tires. Too much air in the tires is just as bad as not enough. I teach this daily to my students as well. If the tires are not inflated per the vehicles specs, tire wear and pulling issues will develop as the tire is not having the proper contact with the pavement. Here is a link with more info also.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=8

Each brand / size of tire will have a different max rating. The tires on my 1 ton dully are set at 85psi when the MFG rating for my truck suggests a psi of 65. Sorry but I know tires and you should know that the tire MFG knows more about their compound / build then any auto MFG. Going off what the auto MFG prints in a book is just crazy. I have worked with many different tire MFG over the years with my racing and I know for a fact that every tire MFG has different compounds and ratings for the same size tire.

Steve you need to come spend a weekend at the track with us and I`ll show you what 1 psi can change you might be shocked.

 

[Chris Gullikson]

I like to drop a 1/4 of a pound out of the right front as peak heating is reached, helps free up the van going into the corner.

 

[Steve Polley]

Each brand / size of tire will have a different max rating. The tires on my 1 ton dully are set at 85psi when the MFG rating for my truck suggests a psi of 65. Sorry but I know tires and you should know that the tire MFG knows more about their compound / build then any auto MFG. Going off what the auto MFG prints in a book is just crazy. I have worked with many different tire MFG over the years with my racing and I know for a fact that every tire MFG has different compounds and ratings for the same size tire.

Steve you need to come spend a weekend at the track with us and I`ll show you what 1 psi can change you might be shocked.

Steve and Adam, my post above applies to stock applications and stock vehicle that have been unmodified. Changing tire sizes and tire types is a whole other can of worms I wont get into. My statement applies to stock applications which as a whole is most of the general public vehicles. By varying the tire pressures, you run the risk of uncecssary tire wear. We see alot of people come in wanting an alignment because of tire wear and most of the time it is just a matter of proper inflation.

Steve, I dont disagree at all in the aftermarket/racing world that the tire rules are different for inflation. Thats completely different for the OEM side of things.

 

[chadvia]

Wow, I've never seen such a debate on tire inflation. IMO, at least you are inflating your tires and not driving around with about 15psi like I often see on the highways.

 

[Jason Foster]

I too have done extensive reading for years on the topic. It is true to go with the tire manufacturer if the tire size, type, or function (ie snow tires) is completely different than stock. Regardless of the compounds and tire design, it is the weight load and distribution that tends to matter. If there is a drastic difference in tire labeled psi, and manufacturer psi, I would recommend looking further into why. If in doubt, call both the tire manufacturer and a local dealer and get the number of a tech at corporate you can speak with about it.

But at the very least...go out and check the tires, regardless of how you feel what it should be....bottomline for this thread is to remind folks to check their tires and spare tire.

 

[James Hammett]

The warnings against over-inflating your tires because you'll get uneven wear and a dangerously small contact patch have not been valid since the days of bias-ply tires. The steel belt in radials keeps this from happening.

Whether or not over-inflating your tires gives you better gas mileage seems to depend on the car. Subaru recommends that my front tires be inflated to 32. This feels and looks and by other owners' accounts IS too low. I have them inflated to 40 and while I haven't done any testing w.r.t. gas mileage the elimination of the major sidewall bulge tells me rolling resistance HAS to be less.

I should note that I've kept the front/rear inflation ratio the same as the OEM recommendation. I can't find the link right now but I've read an article that recommended a good starting point for over-inflation is 10% under sidewall PSI max to allow for thermal expansion and then some. Then adjust for proper front/rear inflation ratio.

 

[James Hammett]

I should add, one safety advantage of over-inflating is that if you don't check your inflation as often as you should your tires won't ever become dangerously under-inflated (this can happen quickly going into winter!)

 

[Steve Polley]

James, do you have a website that you can reference this info? This really goes against what we have been trained as ASE Master techs to do. Over inflation causes center tread tire wear and less contact from the road. This is covered as well in all the books we use in our classes. TPMS systems are also very picky about the proper inflation as well.