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Old 03-26-2008, 07:35 AM   #1
CLETUS
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air Pressure Question

We have probably beat this one to death but I got to ask.

The sticker on my chain gaurd says that I should have 32 PSI in the front tire and 36 PSI in the rear.

All the other bikes I have seen say you need 36 PSI in the front and 34 or 36 PSI in the rear.

Why would one bike be at a lower pressure in the front than the rear?
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Old 03-26-2008, 09:47 AM   #2
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Old 03-26-2008, 09:47 AM   #3
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could be lots of things. suspension for one.
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Old 03-26-2008, 09:49 AM   #4
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oh, and are you still using the old winter air? you should have put spring air in like a week or two ago,.
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Old 03-26-2008, 09:54 AM   #5
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Quote:
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oh, and are you still using the old winter air? you should have put spring air in like a week or two ago,.

check the tire sidewall for the recommended tire pressures, but as others have stated, different tires, different bikes, different riding application will all require adjustment and varied tire pressures.
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Old 03-26-2008, 10:12 AM   #6
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The tires are the stock tires for the bike. Daily commuter bike.
Front: Bridgestone G549, 110/70/H17
Rear: Bridgestone G550, 130/70H17
The bike is a 2006 Kawasaki Ninja EX500.

The tires on the other bike are stock for street play.
Front: Bridgestone BT014, 120/70/ZR17
Rear: Bridgestone BT014, 180/55/ZR17
The bike is a 2007 Suzuki GSX-R600. For goofing off.

The ninja wants 32 PSI in the front and the gixxa want 36 PSI. Both want either 34 or 36 PSI in the rear.
I was wondering why the ninja is lower in the front. I guess it could be the size of the tire, but it sounds a little off.
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Old 03-26-2008, 10:30 AM   #7
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The tires are the stock tires for the bike. Daily commuter bike.
Front: Bridgestone G549, 110/70/H17
Rear: Bridgestone G550, 130/70H17
The bike is a 2006 Kawasaki Ninja EX500.

The tires on the other bike are stock for street play.
Front: Bridgestone BT014, 120/70/ZR17
Rear: Bridgestone BT014, 180/55/ZR17
The bike is a 2007 Suzuki GSX-R600. For goofing off.

The ninja wants 32 PSI in the front and the gixxa want 36 PSI. Both want either 34 or 36 PSI in the rear.
I was wondering why the ninja is lower in the front. I guess it could be the size of the tire, but it sounds a little off.
Could be the weight distribution of the bike.... the gixxer probably has the engine riding to the middle/rear of the bike while the EX500 has the engine more to the front... I don't know, to be honest with you... just a guess.
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...... but when i have problems being able to screw other things i normally tie them up and lube the out of it. dont be afraid do get rough with it. if you cant handle it with the tool you have maybe the task is to hard for you. in which case if could be time for some tag team action and maybe even a foursome...
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Old 03-26-2008, 10:58 AM   #8
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What kind of riding do you do? This needs to be answered before hand. Working with the person that sold you the tires is always the best person to ask about pressures.
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Old 03-26-2008, 11:05 AM   #9
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I'd run the suggested on the Ninja for cruising (better gas and tire mileage)

I'd run lower than suggested on the GSXR while "playing" (30/30 maybe)

Why don't you come "play" on the track? It is SOOOO much more fun than doing it on the street!
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Old 03-26-2008, 01:07 PM   #10
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Quote:
Originally Posted by Pre-K View Post
I'd run the suggested on the Ninja for cruising (better gas and tire mileage)

I'd run lower than suggested on the GSXR while "playing" (30/30 maybe)

Why don't you come "play" on the track? It is SOOOO much more fun than doing it on the street!

I'm on my way. I bought an '05 SV that is track ready. I'm working a few track days to get info on how that all works since it is new to me. I should be out there in May or so. I still have a few things to collect and get right. I like to have everything perfect.

My fun bike (da Gixxa) is for SMR, rides through the country, etc. Sometimes I like just having a quick bike for spirted rides. I will more than likely buy a liter bike next year and convert the gixxa to a track bike for larger tracks. Haven't made up my mind yet and have a year to decide.


My riding on the lil Ninja is just regular riding to work, etc at normal traffic speeds. It is more comfortable in traffic than a SS bike. I picked it up b/c I got a really good deal on it and I wanted to ride around with my daughter.
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Old 03-27-2008, 08:45 AM   #11
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The 250 will work well with 32 / 34, the GSXR will do well with 36 / 34 for most street use.
Track use is a different subject.

Hope this helps.
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Old 03-27-2008, 08:55 AM   #12
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I still have trouble setting up air pressure with diffrent temps.
on a hot day 29 / 31 or 28/30 seems to work great but in the cold or cooler weather I'm catching finding a good temp
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Old 03-27-2008, 09:04 AM   #13
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I still have trouble setting up air pressure with diffrent temps.
on a hot day 29 / 31 or 28/30 seems to work great but in the cold or cooler weather I'm catching finding a good temp
Erik,
Is this on your race tires?
If so, I'd suggest consulting with John / kawi jm, our residant Bridgestone race tire guru.
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Old 03-27-2008, 09:05 AM   #14
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That's my default answer on air pressure questions at the track.
Man I feel like a noob
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Old 03-27-2008, 10:12 AM   #15
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Quote:
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That's my default answer on air pressure questions at the track.
Man I feel like a noob
Don't feel like a noob Erik. There are many factors that can influence your tire setup. Obviously your suspension and geometry are one of them. Track conditions, wind and your riding pace can influence how your tires work.

Before I go into all of that I want to address the issue of choosing compounds. I usually suggest a compound based on optimum grip and ease of use. For example: Say your a fast "B" group rider, but you don't quite feel comfortable in "A" group (the average pace is a little too fast for your liking). If it is cool to moderate in temp; I will usually suggest a Soft front & rear. This tire usually will last 2-3 trackdays and will supply all the grip you will ever need. It also gets up to temp easier, therefore your pace will keep the tire working in it's intended temp range throughout your session.

Now back to the pressure issue. 28 front - 25 rear cold pressures for BT002 Pro's. You can play with pressures just like some people play with thier suspensions. It is not set in stone, BUT (speaking for Bridgestone) there is a operating range that the tire works best in. On track pressures 32-34 psi front & rear is the operating range for the BT002 Pro's. The tempurature window is pretty large at 155 F - 220 F, So a set of properly working warmers at 175 F puts you inside the temp range but towards the bottom range. On the warmers I have been setting people up at 30 Front & 28 rear. Thats fully hot (Wheel warm) on the warmers. 1st session or two CHECK YOUR PRESSURES directly off of the track. If you do this and get the pressures to be consistently in the operating window; then your good to go for the day. Keep them on the warmers all day at 175 F. As you can see the tire can operate at a much higher temp so you can't "cook" them on the warmers. Again these are Bridgestones I am refering to here.

Back to the Compounds. All tires are constructed pretty much the same in that the carcass is built, then there is a base rubber, then a outer layer of rubber. That outer layer is the working layer or premium rubber. It is VERY important to choose the proper compound for the given situation. Now I understand that everyone can't carry around one of each compound, but replacing bodywork and paying off hospital bills will be more expensive. For most riders (trackdays) a soft front and medium rear works perfect, but in early season a soft rear may work better. This is why; in really cold and/or windy conditions to keep heat in a medium rear may require more pace than you can muster. As the tire cools you will tend to spin it. As it spins, 2 things are happening. The carcass is cooling and the surface is getting heated in a very specific place on the tire. Your going to essetially spin off the "premium" rubber and be left with the base rubber. Again the base rubber is not junk, but the grip is diminished a little than that of the premium outer layer. In extreme cases you will "Cold Tear" the tire. That is when the carcass is fully hot but the surface is cool or cold. That is when you see the outer layer torn off. It looks absolutly terrible, and is a totally different thing that the outer layer "spinning" off. Cold tearing destroys the tire, the other just diminishes the grip of the tire. Cold tear can be avoided by using some simple techniques. Leave your warmers on for 45 minutes...minimum; you want the wheel to be warm. Also don't take off the warmers until you are geared up and ready to roll out, don't hangout in the pits smack talking too much waiting to roll out on the track. This is the perfect way to cold tear a tire. The carcass will be hot from the warmers and the longer you sit in hot pit, the more the surface cools. You go out and start running hard right off and you may ....again may cold tear the tire. It will not happen everytime, but you are certainly making the conditions as so. When it is cool, a soft may last longer than a medium, the soft will be gripping and working properly where the medium may working fine at first then start to spin and as mentioned before you can spin off the outer rubber. This is mainly during the cold/cooler months. We are starting to get into the warmer months and the soft front and medium rear would be in order. Until it gets into the upper 90's I would not suggest a medium front.

I hope all of this info helps you guys have fun out on the track as well as explain some things you may have seen and experienced.

John
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