View Full Version : What About Tyre Pressures?
RiderInBlack
12th May 2004, 14:42
What about Tyre Pressures? How do you guys workout what is best for you for:
Racing. Before and in between races. For different conditions (dry to wet, etc)
Road (Normal, Commuting, Pillion, Packs, etc)
With the VFR750 and the CBR1000FL I've been told that Front 36psi and Rear 42psi (cold) are fairly standard, but after getting the P-Diab's fitted at Leading Edge I have been told that this varys in relation to bike usage and road conditions. For Track they told me 32-34psi for the front and 35-38psi rear, and for Touring 38psi Front and 42psi (44psi with pillion) Rear for my CBR1000FL. I am experimenting with tyre pressures now to see what feels right for me, and am interested to what you feel for when setting the tyre pressures for your bikes.
vifferman
12th May 2004, 14:58
Dunno about track (never had my bike on one, although I've ridden a few bikes at Pukekohe), but on the road I've found that sticking with 36F/42R on the VFR worked best, and it seems the same for the VTR.
The previous owner of the VTR ran much lower pressures with the Pirelli Dragons (EVO/GTS), and the tyres were shagged. I eventually removed most of the squaring off - which I believe was caused in part by too low pressures - but they never felt good.
Running lower pressures allows the tyres to heat up quicker due to the carcase and tread flexing, but a tyre has a limited number of 'heat cycles' in it, and once this is exceeded, it's done, even if there's still tread left. For a race tyre, this may be only a handful of races, and is why using race tyres on the road is not necessarily a good idea. Also even though the flexing/heating makes the tyre stickier, it wears the tyre out faster, and may cause cracking around the tread blocks. It may also make the tyre a little more prone to damage from potholes and the like (but not here - we have such perfectly maintained roads, eh?)
It's largely a subjective/personal thing. F'rinstance, the Azaros I've now got on the VTR (luvly tyres) apparently don't like to be run at lower than recommended pressures. Then again, I don't like lower pressures, because of the 'squirmy' feeling it induces.
What you need to do, is record the pressures before and after a ride, and see how much the pressure has gone up. It should rise by no more than about 5-10% of the cold pressure.
MikeL
12th May 2004, 15:04
It may or may not be a coincidence, but I've found with all four bikes I've had that sticking to the recommended pressures within 1-2 lb/sq in feels best. When I put air in I set the pressure to 1 over the recommended figure (don't know how accurate these things are). In most cases I can ride for about 2 weeks before it starts feeling a bit different, and when I check the pressure has usually dropped to 2-3 lb/sq in below the recommended figure.
When I went on the track i didn't change the pressure and was quite happy with the way it felt.
Hitcher
12th May 2004, 15:08
I work on the assumption that the manufacturers must know what they're talking about, and run my tyres at their recommendations, maybe plus 1psi.
For the Zrex that's 37psi front and rear.
Mrs H's Marauder runs 29psi up front and 33psi rear.
There's a great fitment guide on the Dunlop UK web site that will tell you recommended pressures for the make, model and year of your ride. It doesn't go into subtleties such as track or road, wet or fine, sweet or sour, over and under...
Hitcher
12th May 2004, 15:13
According to the Metzeler online fitment guide, your Honda VTR1000F should be running Rennsports, at 2.5 BAR front and 2.9 BAR rear.
aff-man
12th May 2004, 15:16
the zxr has 32psi in the front (mtr01) and 35psi at the back (gp80) normally and i usually drop it 1 to 2 psi when riding 2 if it's a hot day 1.5 is warm ect...
RiderInBlack
12th May 2004, 15:20
Last Bike-only Day @ Puke I tried 36psi front and 40psi rear set after riding from Barry's Point to Puke (had been set at 36psi and 40psi @ Leading Edge that day and was showing 40psi and 48psi on arrivial), which seemed to stick well. Just curious as to what feedback you use to judge the "right" psi for you.
Have read this Thread on Tyre Pressure (http://www.kiwibiker.co.nz/forums/showthread.php?t=1164&highlight=Tyre+Pressures), which has been good (especially the bit by WKO), but feel I need more info.
vifferman
12th May 2004, 15:33
According to the Metzeler online fitment guide, your Honda VTR1000F should be running Rennsports, at 2.5 BAR front and 2.9 BAR rear.
Is that so?
What's a BAR?
What's a Rennnnnnnsports?
Is that so?
What's a BAR?
What's a Rennnnnnnsports?
1 bar = 14.5037738 pounds per square inch
Kind of tyre :) http://www.metzelermoto.com/product_info/catalogo/scheda.asp?ID=168&idCat=15
vifferman
12th May 2004, 15:44
1 bar = 14.5037738 pounds per square inch
Kind of tyre :) http://www.metzelermoto.com/product_info/catalogo/scheda.asp?ID=168&idCat=15
So I need to run my front tyre at 36.2594345 psi, and my rear one at
42.06094402 psi.
Hmmm... So where am I going to get a tyre pressure gauge that reads that accurately?
I don't reckon them Rennnnssssportz - they appear to be made from elephants.
White trash
12th May 2004, 16:20
30 front, 32 rear.
So there ;)
pete376403
12th May 2004, 16:35
1 bar = 14.5037738 pounds per square inch
Kind of tyre :) http://www.metzelermoto.com/product_info/catalogo/scheda.asp?ID=168&idCat=15
I Bar = atmospheric pressure at sea level (can also mean Browning Automatic Rifle)
(OMG I've introduced guns to the thread)
Jackrat
12th May 2004, 16:35
I set my pressures to what the book say's.
If I alter from this it is up, not down.Set right an the bike rolls in nicely,let the front end get low and it front becomes very slow, heavy,and hard to change lines plus I can feel the fork flex a lot more.Let the rear get down and it feels like I'm towing a trailer plus it will weave in corners.With firm tyre pressures and the suspension set firm the bike handles a lot better than legend would have it.
vifferman
12th May 2004, 16:47
Y' know - what this thread needs is:
Bike model
Type of riding (commuting, touring, etc.)
Laden weight (rider weight, passenger? luggage?)
Type of tyres (make, model, size)
Riding style
Tyre pressures.
So for me, it's:
VTR1000
Commuting in all weathers, try to stick to backstreets
87 kg, plus 10kg of backpack, plus gear, rarely a passenger
Avon Azaro AV49-SP 120/70-17 front, AV46-ST 180/55-17 rear.
Mostly careful, but with some hooning (wheelies, stoppies, etc.)
36 F/42R
madandy
12th May 2004, 17:11
RF400
Commuting in all weather, open road plus weekend blasts
94kgs + sometimes a pillion
Metzeller MeZ4 120/70ZR17f 160/60ZR17r
cruisy, high speed riding
34psi (f) 40psi (r)cold.
aff-man
12th May 2004, 17:17
89' zxr250a
commuting in all weather + weekend blats
60-61 kg (depending on before or after lunch ride)+ 5kg pack when commuting
pirelli mrt01(f) and dunlop gp80(r)
32(f) 35(f) and -2 for big rides
Coldkiwi
12th May 2004, 17:18
Y' know - what this thread needs is:
GSXR 600
fast commuting/weekend thrash/track
bike: 170kg, rider 65kg... rarely any luggage of note
Pirelli Diablo Corsas
Riding style: move around on the bike like there's ants in my pants!
Pressures: 31psi on front, 30 rear used this setup at pukekohe after playing around abit. Above this, the tyres squirmed a bit and below this they stuck better but started wearing too fast for my liking. With knee down riding, the rear forms nice orange peel wear. Behaves just fine for my commute as well!!
Bandito
12th May 2004, 17:33
:crazy: After much searching I have found 35psi front & 39psi rear the go for my Bandit 1200 running pirelli dragon GTS. I carry a hand held digital tyre pressure gauge (highly recommended) and only alter the rear to 42psi for passenger work. But its safe to say every bike is different so pays to experiment changing only one tyre at a time.
Big Dog
12th May 2004, 17:53
89' Gsx1100f
Commuting in all weather + weekend blats
150-151 kg (depending on before or after lunch ride)+ 5kg pack when commuting
bridgstone(f) and (r)
38(f) 42(f)
Regular appearances by the pillion.
I ride at the reccommended pillion pressures as the single rider pressures are for a 75kg rider, and riding at the lower reccommended pressure has had a hand in a spit valve and causes my tyres to square quite quickly. With the extra two pounds the rear tyre is nice and round and still has about another 2000 kms on it and the front has plenty of tread in the middle and some tread on the sides after 20,000 kms. As a result the front stops quite nicely even in the wet but can get a little ugly on the tamlines.
wkid_one
12th May 2004, 18:50
What about Tyre Pressures? How do you guys workout what is best for you for:
Racing. Before and in between races. For different conditions (dry to wet, etc)
Road (Normal, Commuting, Pillion, Packs, etc)
With the VFR750 and the CBR1000FL I've been told that Front 36psi and Rear 42psi (cold) are fairly standard, but after getting the P-Diab's fitted at Leading Edge I have been told that this varys in relation to bike usage and road conditions. For Track they told me 32-34psi for the front and 35-38psi rear, and for Touring 38psi Front and 42psi (44psi with pillion) Rear for my CBR1000FL. I am experimenting with tyre pressures now to see what feels right for me, and am interested to what you feel for when setting the tyre pressures for your bikes.Next to impossible to give a standard answer to this. Soooo many variables. In an ideal world you should know what you HOT tyres pressures should be, not cold. As from cold - so many things affect the tyres and how hot they get - therefore the effective working pressure of the tyre - road surface, road temp, ambient temp, bike weight, bike weight bias, riding style, camber of road, speed of riding, tyre compound, tyre shape, rim size etc etc etc
Track riders and racers spend fortunes with studying the hot temps of the tyres - not the cold as the cold means feck all to them.
I ran 36 front and 38 rear - but then I ran Rennsports which need to keep heat in them.
You want to look for things like cold tearing on the tyre - which would tend to suggest the tyre isn't get hot enough and things like this. At the end of the day - you will know through your backside if you tyres are at the wrong pressures.
Best thing to do is ride on the manu reco tyre and pressures....if you are unsure that it. Other than that - a seat of the pants gauge is next best.
There is another thread floating around about this also.
Try this thread http://www.kiwibiker.co.nz/forums/showthread.php?p=14921#post14921
Rule of Thumb - less pressure equals hotter tyre, more pressure equals colder tyre.
wkid_one
12th May 2004, 18:51
Y' know - what this thread needs is:
GSXR 600
fast commuting/weekend thrash/track
bike: 170kg, rider 65kg... rarely any luggage of note
Pirelli Diablo Corsas
Riding style: move around on the bike like there's ants in my pants!
Pressures: 31psi on front, 30 rear used this setup at pukekohe after playing around abit. Above this, the tyres squirmed a bit and below this they stuck better but started wearing too fast for my liking. With knee down riding, the rear forms nice orange peel wear. Behaves just fine for my commute as well!!
Yes Rich - I remember having to lend you my pressure gauge and footpump to sort all that fiddling around out!
Deano
12th May 2004, 20:33
Shit, I am going to have to have a rethink here. I was running 35f (BT010), and 32r (Diablo) in summer. (32f and 29r on Manfeild in summer)
With the cooler weather the front was squaring off leaving ridges about 10mm from the edges. I was told to try more pressure and now have 38f and 35r, which has helped to shave those ridges off the front. The rear skipped a bit more on the road corrugations mid corner but had relatively good feel to it.
From what Ive read, everyone has more psi in the rear.
Feck, I might be able to get a few tenths of a second here, eh Jimbo ? :Pokey:
Grumpy
12th May 2004, 21:40
I remember reading an article sometime ago about the differences between the bike manufacturers recommended tyre pressures and the tyre manufacturers recommendations.
The conclusion was that the tyre fellas set their pressures to give optimum performance and durabilaty where as the bike fellas set theirs to make up for what their suspension may be lacking.
I suppose anywhere in between those two points would suffice.
I have to admit that I tend to base my settings on the life of the tyre more than anything. It doesn't take long to work out what is a good comprimise between good wear and good performance.
I set my pressures on the 1400 at 40-42psi on the rear and 38psi on the front. This seems to work pretty good.
FROSTY
12th May 2004, 21:45
ok so Im out of touch here - i used to stick to a universal 36psi rear and 32 psi front
Holy Roller
12th May 2004, 22:18
I run dunlop arrowmax on the the rear at 40 any thing under and the bike feels like the tyres are folding over in the corners. The front is a TT 100 at 38 feels just right for my riding style.
jimbo600
12th May 2004, 22:31
30 front, 32 rear.
So there ;)
sounds about right for normal use. Trackday 29psi for both is good, and for long distance work 36psi.
This is from the tyre guru who imports the hoops from Germany and he know's his product.
End of the day I ride like crap so I can put anything from 25psi to 40psi and wouldn't notice the difference.
yessum
12th May 2004, 23:09
28 front, 32 rear ...as per the manual.
Don't feel like i've quite got the experience to second guess those figures :whistle:
Generally check every time I ride, maybe twice a week at the moment.
FROSTY
13th May 2004, 03:06
how much would you guys drop the tyre pressure for a track day?
madandy
13th May 2004, 06:15
Depends on the weather doesn't it?track temp and all that.
Cajun
13th May 2004, 11:53
Bike model = 04 gsxr600
Type of riding = commuting & weekend canes
Laden weight = 65ks and about 2kgs for bag, on back, wallet silly phone, keys, and bottle of V
Type of tyres = bridgestone 014 front and rear came with the bike
Riding style = boring just around town is basic, but weekends its starting to get the knee down
Tyre pressures = running at suzuki stardard 36 front and rear, when it goes on the track i will lower them a little bit,
magnum
13th May 2004, 13:35
between 34/36 front and back,track days ill drop 2psi/tyre so 30/32,diablocorsas.
scumdog
13th May 2004, 14:22
According to the Metzeler online fitment guide, your Honda VTR1000F should be running Rennsports, at 2.5 BAR front and 2.9 BAR rear.
What the hell a Browning Automatic Rifle got to do with tyre pressure - except maybe letting the pressure down sort of real quick?
Seriously, I'm a dinosaur and it's always psi to me - and h.p. and mpg :weep:
The mental gymnastics I go through to convert litres per 100 km to m.p.g. just about gives me cranial meltdown :eek: why is it not km per litre?
RiderInBlack
13th May 2004, 15:45
Bike model: Honda CBR1000FL (:spudwhat: fu*ken heavy, 2 to pick up if it's on it's side:doh: )
Type of riding (commuting, touring, etc.): Mainly Touring and Commuting (open road 40Km+). The odd hoon:rolleyes:, specially if I am chasing/try to keep up with other riders :msn-wink: Some track time to improve skills and to help set the bike up better (no real racing). No off-road if I can help it:bleh:, but do have a Km strip of metal road to get to my home.
Laden weight:
Rider - 85Kg
Passenger - at times. Around 75-85Kg
Luggage - Touring: kitchen sink if I can get away with it:bleh:
Commuting: 20Kg:spudwhat:
Track: None
Type of tyres: Pirelli Diablo
Front - 120/70 ZR17 M/C (58W)
Rear - 180/55 ZR17 M/C (73W)
Riding style: Varies. Am trying to get my knee down on the track but have only touch the tip of my boot and the underside of my foot pegs (just, once going around the "Hill" corner leading to the home straight @ Puke).
Tyre pressures:
Trailing various pressures at the moment for different rides/conditions
Normal commuting on dry open-road - Front 36psi, Rear 42psi (cold).
Track Open Days - Front 36psi, Rear 40psi (hot)
Am trying to find best hot pressures for my tyres.
Feel WKO is right that hot pressures are more accurate as this is the temp that the tyres are working at.
If the Volume is constant then Pressure increases/decreases proportionately to Temperature (somebody's law:spudwhat: ).
Big Dog
13th May 2004, 17:15
My understanding of why more air in the rear is the back wheel tips over further (front tyre stays almost vertical on the road) so it needs more pressure to prevent sidewall deformation (less true in modern low profile tyres, especially those with virtually no sidewall).
Front tyres also need to absorb more direct impact so need to be softer so as not to affect steering as much when hitting potholes tramlines etc.
Eg lower tyre pressure = smoother cruising and better straight line grip due to larger contact patch, making stoppies easier.
But slower tip in and less adequate cornering grip (should you need those brakes after all, or want to get the knee down) as your sidewalls will deform less, so direction or inertia changes will be more stable.
A soft rear tyre may squirm without actualy breaking traction under heavy acceleration due to trye deformation, meaning you can't go as hard.
A too hard rear tyre will have little or no grip in the wet while the tyre is cold.
riffer
13th May 2004, 19:38
Bike model = 87 FZR750R 2LM with FZR1000 forks and rear suspension (stiffer suspension) preload set about halfway on front and rear. No idea about fork oil age (never done it) but forks are pretty stiff.
Type of riding = commuting & weekend play
Weight = bike 228kg (wet) + rider 90-95kg + bag 2-5kg
Type of tyres = IRC SP11 120/70-17 front, Dunlop Sportmax 205 160/60-18 rear
Riding style = mainly keeping to the speed limit commuting, lanesplitting as much as possible, try to find corners as much as possible in the weekends but tend to ride smooth rather than ridiculously fast.
Tyre pressures = 36 F, 42R measured cold for the road. Haven't been to a track day so no experience.
TonyB
14th September 2004, 08:22
I'm a dinosaur and it's always psi to me - and h.p. and mpg :weep:
The mental gymnastics I go through to convert litres per 100 km to m.p.g. just about gives me cranial meltdown :eek: why is it not km per litre?
Never fear, go here: http://www.metroyamaha.com.au/tools.htm#torque
TwoSeven
14th September 2004, 13:00
This is the rather bizarre way I work out tire pressures.
I ride my bike around a lot and write down the tire pressures that I feel comfortable with when the tires are hot. My notebook would contain the air-temp and tire pressue (since I use the same brand of tires, most of its in my head now).
General method is to take a pressure that is slightly hard, ride the bike till the tires are warm and every now and again let a psi out (using an accurate guage). When I like the feel, thats the one I keep.
When the bike cools down again, you need to re-measure your tire pressure to find out what the cold value should be (so when you initially inflate the tires what to put in).
Also try and make a note of how long the tires took to get warm for that air-temp). I dont have a thermometer for this, so I just guess.
For racing, its just a matter of working out what the current air-temp is, then finding the appropriate warm setting in your log book. If the tires are cold, set it to the cold setting (and remember how long it will take to warm up - this is how many slower laps you need to do). If using tire warmers, then the warm up laps will be reduced).
Writing down the cold setting after the tires have cooled saves you from having to calculate tire pressure expansion as the tires warm up. When I did track days and the like, I measure the tire temp as soon as I come in, then 15 mins later and how I thought the bike felt. Next day I can sit down and work out the ideal settings. It means next time you get similar conditions you can be more accurate.
Also remember that tires cool down real quick (different brands at different rates), so if you are scratchin and slow down for a while, or stop at some lights, the tires will cool. Helps prevent the slide due to suddenly code tire syndrome.
I know this method sounds a bit like hard work, but at the end of the day, you can ask someone else for some settings, but that means the info they will give back will be their preference for their riding style, bike, type of tires and may not be suitable for you (it does give you a good ballpark tho). Since you will be out riding your bike - why not write down the settings every now and again.
For road use I often run way harder than track pressures. I can be anywhere from 33/33psi (D207s) to 36/38 on the road - depending on the mood I am in and the feedback I am getting (I hate dunlops out of interest).
wildfire1
14th September 2004, 13:27
Start with what the hand manual says.
Then look at what the Tyre Manufacturer recommends
split the difference and you will always have the perfect cold tyre pressure
Or Not.....
It's just a matter of experimenting in differenct conditions :scooter:
Some people are heavier, some are lighter, some sit more forward, some carry luggage....get my point.
Hoon
14th September 2004, 15:03
For racing the way I calculate my tyre pressures is measuring the difference between hot and cold. I measure my pressures before I go out and then again as soon as I get back to the pits.
I forget where I read it but you should be aiming for a 6-8 psi increase between cold and hot pressures.
- If you are getting less then you are running too much pressure and the tyre is not flexing enough to generate the heat required to reach optimum grip.
- If you are getting more then not enough tyre pressure as the tyre is squirming around too much.
I find this method more accurate than "what my mate bob uses" or "what manufacturer x recommends without even knowing what type of bike, track conditions, my weight or riding style I use" but it doesn't take into account whether you're in Antartica or Bahrain.
On my RGV I use to have more pressure in the rear however with the ZXR 29-30psi is spot on but I'm struggling to get enough warmth into the front tyre (even at 28psi I was only seeing +2psi when hot and I sure aint going any lower!!!). So I suspect I'm not getting enough weight onto my front end. The fact that I still have another 10cm from bottom of fork travel and steering which I'm sure could be quicker kind of confirms this.
FROSTY
14th September 2004, 15:31
Hoon--I definitely noticed Im not working my front tyre as hard at Pukie as at Taupo.
I'm wondering if it's the nature of the track with only one real braking point but a lot of flat out riding.
I was definitely noticing a similar temp change
Another thought was that I noticed im sitting back furthur at pukie not loading up the front as much into corners.
Sensei
14th September 2004, 18:11
36 F / 38R as they will go up around 4 PSI when hot
:niceone: Sensei
DEATH_INC.
14th September 2004, 18:38
http://www.korteng.com/KWjpg/1918a2.jpg
'99 Gixx 7fiddy,90something kg rider,no one game enough to pillion,no luggage,various sport tyres......
32psi front 35psi rear generally for road use,no track riding.
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