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Discussion Starter · #1 ·
As a general rule,is everyone using the standard tire pressure in fronts and rear tires?

Or is someone using different pressure settings?
 

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As a rule, unless I have aftermarket tires, I keep them at what the Owner's Manual says.:thumbs:
 

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I sent a PM to another forum SKY owner just this AM for an Answer. I'm going to the NC mts Thursday to run the DRAGON (Hwy 129, with 318 curves in 11 miles) love it on my motorcycle, looking for fun also in the car.

The SKY manual says the posted "door sticker" 29PSI is MINIMUM air pressure. I don't have my SKY at work today but it seems like the tires had 40psi written on the side..or at least a lot higher max then the door. I'm running 31-32psi....WHAT SHOULD I RUN?
 

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Sunny Ragtop said:
I sent a PM to another forum SKY owner just this AM for an Answer. I'm going to the NC mts Thursday to run the DRAGON (Hwy 129, with 218 curves in 11 miles) love it on my motorcycle, looking for fun also in the car.

The SKY manual says the posted "door sticker" 29PSI is MINIMUM air pressure. I don't have my SKY at work today but it seems like the tires had 40psi written on the side..or at least a lot higher max then the door. I'm running 31-32psi....WHAT SHOULD I RUN?
I ran the Tail of the Dragon years ago on my Buell Cyclone that was great fun. I would love to make it back up there with Little Missy. You enjoy yourself and be sure to post some pictures. :thumbs:
 

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Discussion Starter · #5 ·
I had checked my tire pressure this weekend and discovered different tire pressure on all my tires.
It ranged from 32 to 39.
I guess 32 is a happy medium.
Anyone have input on this subject?
 

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The wife has the Sky today, so can't check the book or whosit plate (usually on the door sill that lists tire pressure) but if it is between 29 and 40, I'd run about 35 psi (cold).
 

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The best I can suggest on tire pressure is check them when they are cold in the morning. They should be around 29-30 lbs if that is the recommended minimum pressure.

As you drive your tires heat up. When tires heat up, their air pressure rises. On hot days this is even more critical. If you inflate your tires to 35 PSI when cold and the max is 40 you do have the possibility of the pressure inside the tire rising above the maximum allowable pressure. Also, the harder you drive the more heat gets into the tire. So cruising at 35 on a straight highway will produce less heat than driving 70 on the freeway which will PROBABLY produce less heat than cutting through a twisty mountain road full tilt.

Now, if you're asking what is the correct pressure to get optimum traction from your tires...well...Perhaps someone here has done the work and knows what that would be on the stock tires.
 

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My advice: run 'em at 29PSI when the car has not been driven.

I've felt significant effects (hard, bouncy ride, skipping on bumpy corners, generally jittery overall feel) with pressures on THESE tires much above 34 PSI.

Your dealer SHOULD be setting them to the tire sticker in your door.
 

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(((( 29 ))))

JFig said:
I had checked my tire pressure this weekend and discovered different tire pressure on all my tires.
It ranged from 32 to 39.
I guess 32 is a happy medium.
Anyone have input on this subject?
i know doesn't sound right cuz been 32 forever on everything else but 32 is a horrible ride and steering changes sooooooooo much !!! back to 29 and stayin there !!! book says 29??? drive the 29 psi - unbelieveable difference !! BIG BIG difference
 

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Sunny Ragtop said:
I'm going to the NC mts Thursday to run the DRAGON (Hwy 129, with 218 curves in 11 miles) love it on my motorcycle, looking for fun also in the car.
Ooooh I'm jealous...did the Dragon in 2004 on my Harley...what a rush!!! :thumbs: By the way...you're off by 100 curves...it's actually 318 curves in 11 miles. :D Have fun and be careful out there...watch out for those semi's that take up both lanes. :eek:
 

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Run the tires at 29 psi cold and you will be replacing them in 20K miles or less. Keep them at 35 psi minimum and they will go for thousands more. Your fuel milage will also increase. The car will ride firmer and not be "mushy" and soft. The door sticker recommending 29 psi is for those who purchased a Sky but want it to ride more like a Caddy than a sports car.
 

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Way2Fast said:
Run the tires at 29 psi cold and you will be replacing them in 20K miles or less. Keep them at 35 psi minimum and they will go for thousands more. Your fuel milage will also increase. The car will ride firmer and not be "mushy" and soft. The door sticker recommending 29 psi is for those who purchased a Sky but want it to ride more like a Caddy than a sports car.
Thanks ALL....My dealer did not know for sure either since the manual CLEARLY states 29psi is MINIMUM and tires have 44MAX.

I will run 31-32 on the interstate & lower back down to 29lbs just before spending the afternoon agressively riding the 2nd & 3rd gear tight curves. Yes, 3 more pounds in the tires make it BOUNCE a give less traction. 2nd gear sharp 90 degree turns (light turing right at a traffic light) I could not break the rear tires loose with less psi, but as soon as I put the psi to 32 my rear end tried to slide around!
 

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Run the tires at 29 psi cold and you will be replacing them in 20K miles or less. Keep them at 35 psi minimum and they will go for thousands more. Your fuel milage will also increase.
29 PSI won't cause premature tire wear to the extent that replacement would be required at 29K. That's ridiculous. Inflate them too high (35 PSI is too high)
and they will wear unevently - the center will wear before the shoulders. The
tires need to be inflated so that the weight is evenly distributed across the entire tread for max durability. Higher inflation also encourages rattles and provides an uncomfortable ride and poor handling.
 

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Goodyear Tires

Goodyear Eagle Tires are high performance, low profile. They require more air than standard profile tires.
On the sidewall max. pressure rating is 44 psi.
I run at 36 psi and use valve stem pressure gages.
The car still has a smooth ride and handling respone is better.
I bought the gages at O'riellys Auto Parts, pack of 4 / $9.99.
cheap investment, relacement tires are $235.00 each
 

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1st Gear said:
Goodyear Eagle Tires are high performance, low profile. They require more air than standard profile tires.
On the sidewall max. pressure rating is 44 psi.
I run at 36 psi and use valve stem pressure gages.
The car still has a smooth ride and handling respone is better.
I bought the gages at O'riellys Auto Parts, pack of 4 / $9.99.
cheap investment, relacement tires are $235.00 each
Well, I'm not going to get into a big PM about credentials. Suffice to say I know my way around a tire.

Having said that, I do disagree. The ride is harsher at 36 PSI. The steering is definitely light and uncomfortable at 36 PSI. The amount of grip available on bumpy corners is SIGNIFICANTLY reduced.

Sidewall max pressures have nothing to do with appropriate running pressures. The P245/45 R18 is low profile - but not REALLY that low. It is the SAME sidewall height as a P205/55R16 tire. NO KIDDING! I would hardly classify that as low profile (yes the aspect ratio is an indicator, but that is only half of the story).

A P245/40 R18? That's getting to be low profile. A P245/35 R18? Now THAT'S low profile.

The other thing that factors into this is the relationship of the load to the max load of the tire. This tire is a 96 load rating. The SKY should have a tire closer to 86 or 88 load rating. This means the tire is OVERSIZED for the application.

When a tire is oversized, you need to use lower pressure, or you sub-optimize the footprint (and the application will 'act' like it is overinflated - generally light steering, bouncy ride, momentary loss of grip on transient-bumpy roads, and mismatched radial rate for the shocks and springs).

Bottom line - you'll be happier with 29 psi. The steering will have better "weight", and it will handle better over a wider range of roads.

But go ahead and try 44 psi - and have a taste of what run-flat tires feel like.

I encourage you folks - don't just take my word or 1st gear's word for it - try it yourself!

YOU EVEN HAVE THE INFLATOR IN YOUR TRUNK :lol:

You could easily pull it out, pump up your tires to 44 psi, then drive it and inch them down to see what it feels like. Try going down to 25 psi (tho I don't recommend you stay there - but experimenting with it shows you what it feels like). You can always use your inflator (which is always with you in your trunk :lol: ) to pump them back up.

:thumbs:
 

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Over-inflation is bad

It has been awhile - but way back when I put something like 36 PSI in the tires on an Acura Legend on a hot day after I had been driving the car the tires were so full of air that even the smallest road surface defect felt like a speed bump and would send the shock and spring into a dance that caused loss of traction and streeing. I had to stop and reduce the pressure before driving any further.

Too low a pressure is not good, and you will get excessive wear on the outside of edges of the tread and the side wall will deflect more in turns. You genearlly see very low pressures either for off road vehicles where the tire squishes around objects to get better traction or in racing applications where the extreme heat of rolling friction increases the temperature and thus the pressue to something closer to a normal driving pressure.

photos of various types of wear http://www.dunloptyres.co.uk/ourTyres/car/tyreCare/

http://autopedia.com/TireSchool/inspection.html

Attached is a diagram from http://www.procarcare.com/icarumba/...a/icar_resourcecenter_encyclopedia_tires3.asp

what we need is for someone to come up with a kit where you attach a strip of material to the tire - then drive over a pad - then peel off the backing to reveal your actual contact patch pattern to help determine if you are properly inflated.
 

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The other part of this for consideration:

As I said before, the max pressure is identified on the sidewall. That is a HARD limit, meaning you should never operate your tire above that limit.

The tire PLACARD identifies the tire size and pressure that the vehicle was DESIGNED to operate. This is set by the manufacturer, and other than is subject to the design limitations of the tire, is NEVER set by the tire manufacturer.
 

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tire pressure

http://www.sportcompactcarweb.com/tech/0208scc_tire_pressure_guide/

In the event that you aren't able to find a recommendation for your car, or the tires on your car are so different from those that were originally fitted from the manufacturer as to be incomparable, we received the following rule of thumb from Oscar Pereda, an engineer for BFGoodrich. He calls it a "realistic starting point," saying it has never been just right, but is a good place to start. The rule is:

(Vehicle Weight in lb/100) + 2 psi at heavier end + 2 psi all around if suspension and alignment are stock.

Example: Stock 911, 3,000 lb.
(3000/100) = 30 psi
Add 2 psi all around = 32 psi
Add 2 psi to heavy end = 34 psi at rear
With modified suspension, the result is 30 psi front, 32 psi rear.

Sounds like 29-30 psi is correct
 

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thankyou kappguy

KappaMan said:
Well, I'm not going to get into a big PM about credentials. Suffice to say I know my way around a tire.

Having said that, I do disagree. The ride is harsher at 36 PSI. The steering is definitely light and uncomfortable at 36 PSI. The amount of grip available on bumpy corners is SIGNIFICANTLY reduced.

Sidewall max pressures have nothing to do with appropriate running pressures. The P245/45 R18 is low profile - but not REALLY that low. It is the SAME sidewall height as a P205/55R16 tire. NO KIDDING! I would hardly classify that as low profile (yes the aspect ratio is an indicator, but that is only half of the story).

A P245/40 R18? That's getting to be low profile. A P245/35 R18? Now THAT'S low profile.

The other thing that factors into this is the relationship of the load to the max load of the tire. This tire is a 96 load rating. The SKY should have a tire closer to 86 or 88 load rating. This means the tire is OVERSIZED for the application.

When a tire is oversized, you need to use lower pressure, or you sub-optimize the footprint (and the application will 'act' like it is overinflated - generally light steering, bouncy ride, momentary loss of grip on transient-bumpy roads, and mismatched radial rate for the shocks and springs).

Bottom line - you'll be happier with 29 psi. The steering will have better "weight", and it will handle better over a wider range of roads.

But go ahead and try 44 psi - and have a taste of what run-flat tires feel like.

I encourage you folks - don't just take my word or 1st gear's word for it - try it yourself!

YOU EVEN HAVE THE INFLATOR IN YOUR TRUNK :lol:

You could easily pull it out, pump up your tires to 44 psi, then drive it and inch them down to see what it feels like. Try going down to 25 psi (tho I don't recommend you stay there - but experimenting with it shows you what it feels like). You can always use your inflator (which is always with you in your trunk :lol: ) to pump them back up.

:thumbs:
i can't talk tire talk and you said it soooooo good - i knew it just couldn't express it
((( driving ))).... 29 feels / handles / rides so much better than just 32..... SUCH a difference........ .... to each his own....
i think try the 29 and you'll "get " it
 

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When in doubt follow the manual for tire pressures if driving on the street and usual oem tires.

Did the dragon a couple weeks ago in the elise, very fun, but doing it on a motorcycle is loads more fun.

For those wanting vicarious thrills, go to www.killboy.com for loads of pics of all kinds of vehicles running deals gap (the dragon). Cherohala skyway is another much less travelled exc road right there.

Chris
 
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