Tyre pressures for a lightweight?

[Merv121]

Right, i've recently bought a K4 SV650s which has now been restricted (yay 33bhp club) that i will be picking up on Saturday, this question is for tyre pressures, on my old CBR125 i had stock tyres(to start) and although recemended 33psi they never felt right so had them on 31 and 29... and the contis after that (which caused my huge crash) would not perform at all in the wet with the front folding at slight lean no matter what psi i tried... as i do not want a repeat of the before, i am only 5 ft 4/5 and around 8stone(ish), does user weight really count much in psi deciding and does anyone have any idea what psi i should have at all?

many thanks

[speedyandypandy]

tyre pressure is normally the thing thats set in stone, it's very wrong to change air pressure to compensate for something else, like you did on your cbr125, you where changing the air pressure when you should have been changing something else, like fork springs and damper spring, changing the set up if it's possible.
The 'correct' air pressure for the sv is 33 front and 36 rear.

[Merv121]

thank you for that, as i said with the cbr i forgot to mention the only time on stock tyres they felt compfortable was on the said pressures i had on, until the new tyres, thanks for the explanation though and i wont be changing pressures again to compensate!

thank you

[jambo]

tyre pressure is normally the thing thats set in stone, it's very wrong to change air pressure to compensate for something else, like you did on your cbr125, you where changing the air pressure when you should have been changing something else, like fork springs and damper spring, changing the set up if it's possible.
The 'correct' air pressure for the sv is 33 front and 36 rear.

I don't tend to follow this school of thought.

There is a recommended tyre pressure set by the manufacturer, it is a great starting point. Often there will be a "normal" and "fully laden" setting, usually the fully laden setting will be higher. At the OP's weight, I wouldn't be moving too far from manufacturer's settings as the bike seems to be setup for someone of a little under 10 stone from the springs anyway. Different tyre manufacturers recommend different pressures for different tyres even if they're in the same size on the same bike.

I have personally run everything from 36/42psi on the road, to 32/33 on track. Plenty of other people go lower than that. This should not be done blindly, and I completely agree that if the bike's springs aren't right, changing the tyre pressures is not the correct fix, but it is one variable, along with spring rate, preload, and damping that affects how the tyre grips.

To the OP: Start with the manufacturer's recommended pressures, as above this is 33psi front, 36psi rear for the standard dunlop D220s. If other tyres are fitted, have a look on that manufacturer's website to see if they'd start with something else. If you're going to try other pressures do so by small margins, and try not to stray too far. As posted by speedyandypandy, make sure that the suspension is something like right rather than just playing with the pressures only. For you, the standard setup shouldn't bee too bad :)

Jambo

[johnnyrod]

I see in recent years a lot of people are saying 36/42, I think this is for high speed stability and extra cushioning on our increasingly pothole-infested roads, with a little loss of grip that you most likely won't notice anyway. On track I use 31/30 but high speed stability isn't really an issue (shrot periods not motorway journeys) but grip is. On the road 33/36. Dead right about fiddling though, just changing tyre pressure is the wrong thing to do until you've seen to the suspension etc. It's not like I'd decide to use 32/32 one day because it doesn't do somethingorother quite right

[NTECUK]

Its deff NOT set in stone.
Diffrent loads and speeds affect the Proflie of the tyre.

[speedyandypandy]

I don't tend to follow this school of thought.

There is a recommended tyre pressure set by the manufacturer, it is a great starting point. Often there will be a "normal" and "fully laden" setting, usually the fully laden setting will be higher.
Its deff NOT set in stone.
Diffrent loads and speeds affect the Proflie of the tyre.

The manual/manufacture will tell you if there is different pressures at different times, is that not the same as set in stone? A normal mortal will not need anything else than 33/36 the 2-4 first years of riding.


I have personally run everything from 36/42psi on the road, to 32/33 on track. Plenty of other people go lower than that. This should not be done blindly, and I completely agree that if the bike's springs aren't right, changing the tyre pressures is not the correct fix, but it is one variable, along with spring rate, preload, and damping that affects how the tyre grips.


I see in recent years a lot of people are saying 36/42, I think this is for high speed stability and extra cushioning on our increasingly pothole-infested roads, with a little loss of grip that you most likely won't notice anyway. On track I use 31/30 but high speed stability isn't really an issue (shrot periods not motorway journeys) but grip is. On the road 33/36. Dead right about fiddling though, just changing tyre pressure is the wrong thing to do until you've seen to the suspension etc. It's not like I'd decide to use 32/32 one day because it doesn't do somethingorother quite right

What does trackdays have to do with normal riding? But since you started down that lane I'll walk along:rolleyes::D

You set a cold/hot pressure and stick with that? Again track & race pressures is even more of a difference, you can't just(well you can but I would never) say I'm on 31/30 or 32/33 and stick with that. On track whatever the manufacture says is even more important, and checking when warmed up by the tyrewarmers and(or) straight after you come in,
to dobbelcheck the pressure, on a day with warm tarmac I might go 30.5 front and 27.5 rear(hot temp), on a cold day it might be more correct with 32 front and 30 rear. What kind off track also comes into play, slow track, fast track, etc etc.

[yorkie_chris]

The manual/manufacture will tell you if there is different pressures at different times, is that not the same as set in stone? A normal mortal will not need anything else than 33/36 the 2-4 first years of riding.

The PR2s were a bit of a bugger, very soft carcass which meant they felt a lot better with higher pressure in back.

However, for this concern of light rider, 33 36 will be as good as anything. That and not running the original rock 'ard tyres or some stupid sports rubber in the middle of winter.

[jambo]

Ah,
So the tyres CAN work at pressures other than those set in stone?

Groovy

[speedyandypandy]

tyre pressure is normally the thing thats set in stone

Ah,
So the tyres CAN work at pressures other than those set in stone?


Hey smart'donkey'(thought I was very clever with this one:rolleyes:) what part off the first sentence I wrote didn't you understand? normally. OP was clearly asking about road riding. yes, no, yes? YES
Manual is not a pretty picture book, it's there to be a information source. If Suzuki says it's 33/36 than that's what it is.

Can you find anywhere I stated that tyre pressures where never to be touched under any circumstances? I think not.
It's very irrelevant to bring trackdays/racing into our answer to op. Keep it simple, less chance for making mistakes.

[yorkie_chris]

What about riding like a complete bell end on the road? I reckon that's harder on tyres than (me on...) a trackday anyway :-P

[speedyandypandy]

What about riding like a complete bell end on the road? I reckon that's harder on tyres than (me on...) a trackday anyway :-P
Can I recommend some new tyres for you then?:D
Funny you should say that, alot of people are in fact faster on a piece of road they like than what they are on the first trackday(maybe even the first few).

[yorkie_chris]

It's the sort of roads I think, I've had supercorsas well chewed, avon vipers melted on my fun roads, but probably just because they're so bumpy, the tyre is half airborne and spinning all the time. Whereas track, yeah it's fast use with lots of cornering force... but on nice smooth tarmac, no gravel or sheep or anything!

[jambo]

Hey smart'donkey'(thought I was very clever with this one:rolleyes:) what part off the first sentence I wrote didn't you understand? normally. OP was clearly asking about road riding. yes, no, yes? YES
Manual is not a pretty picture book, it's there to be a information source. If Suzuki says it's 33/36 than that's what it is.

Can you find anywhere I stated that tyre pressures where never to be touched under any circumstances? I think not.
It's very irrelevant to bring trackdays/racing into our answer to op. Keep it simple, less chance for making mistakes.
Do you think we could keep this civilised? There's really no need to be rude.

You've largely ignored the section put up by myself and others about road riding and focused on the track part which, as you've said isn't that relevent to the road, but I thought was worth mentioning just to highlight that different conditions, might dictate different pressures.

tyre pressure is normally the thing thats set in stone, it's very wrong to change air pressure to compensate for something else, like you did on your cbr125, you where changing the air pressure when you should have been changing something else, like fork springs and damper spring, changing the set up if it's possible.
The 'correct' air pressure for the sv is 33 front and 36 rear.

I felt that, especially if the OP is a new rider, the above might make it seem as if any pressures other than those in the book would be bad, which is just not something I agree with.

I did, however, state that the manufacturer's pressures would be where I'd start.

So we're really all in agreement.

Which is nice.

Jambo

[chezvegas85]

welcome merv, you made the same transition as me. Cbr 125 (05) to sv650, although mines an older model (01 S) thats restricted to 33bhp (for another year now).

[speedyandypandy]

Do you think we could keep this civilised? There's really no need to be rude.

You've largely ignored the section put up by myself and others about road riding and focused on the track part which, as you've said isn't that relevent to the road, but I thought was worth mentioning just to highlight that different conditions, might dictate different pressures.

I wasn't rude, a cheeky fekker yes, have a beer on me, print out this as a IoweU.

Do you really have higher pressure in your rear tyre than in your front tyre when on track? You wrote 32/33, you meant to write 33/32, right?

[Thunderace]

Easy fellas this is all getting a bit unpleasant, @Merv pick what useful info you can from the wreckage of this thread.

I would post my opinion, but I don't feel like getting typed at.:(

[speedyandypandy]

Easy fellas this is all getting a bit unpleasant, @Merv pick what useful info you can from the wreckage of this thread.

I would post my opinion, but I don't feel like getting typed at.:(
oh go on, I promise I won't bite, hard ;)

[johnnyrod]

Thread overboard

[jambo]

I wasn't rude, a cheeky fekker yes, have a beer on me, print out this as a IoweU.
Hope to see you at an AR, we'll have a beer then :)

Do you really have higher pressure in your rear tyre than in your front tyre when on track? You wrote 32/33, you meant to write 33/32, right?
No, I meant what i said:

<ENTIRELY off the original topic>
If i was faster, used tyre warmers, or used softer tyres I'm sure I'd end up with a colder rear than front pressure, as most fast track riders do. However, I've tried lower pressures, and for my road bike, with it's touring tyres, I just seem not to like the feel of it on the out laps with lower pressures. This means it takes me longer to start pressing on during a track session.

I'm working on a track SV at the moment, this may well have sticky tyres, and warmers, so I'll almost certainly end up with a completely different starting pressure setup then.
</ENTIRELY off the original topic>

Jambo

[NTECUK]

Dear John.
I'm A rider of 30 stone .When I ride my 125 I find the tyres buldge out at the botom.
Should I be using Truck tyres ;)

[speedyandypandy]

Dear John.
I'm A rider of 30 stone .When I ride my 125 I find the tyres buldge out at the botom.
Should I be using Truck tyres ;)
Poor 125, it must be crying.:D

[embee]

Speaking from the motor industry point of view........

manufacturers have to give information in handbooks, and just occasionally users will look at it.
Tyre pressures are definitely not "right or wrong". Tyre pressures are a compromise of rolling resistance (hence wear and heat), grip, comfort, noise etc. Vehicle manufacturers come up with information which will suit most users most of the time, and try to keep it simple, hence either giving one set of values or sometimes 2 sets for laden/unladen. That's about as far as you can go before it just gets too confusing for a handbook.

If you understand what you're doing, it's perfectly OK to try small departures from the quoted values, after all the pressures will vary with speed/temp anyway. If you find it all bewildering then just use the quoted values.

I have some Metz Z8's on my SV now, and they feel very compliant and to my mind feel generally better when a little higher than the book 33/36, so I use around 35/38.

[NTECUK]

What about when you mix tyres .
Then we have more variations .
I have a Road Attack sports touring tyre on the front and a Corsa III on the back.:o
And Friday i'm going to meet up with the other half in the peak district with all them wet windy roads .
How irresponsible is that !!!

[speedyandypandy]

And Friday i'm going to meet up with the other half in the peak district with all them wet windy roads .
How irresponsible is that !!!

Is it not nicere to meet up in a hotel than on wet windy roads?
Yes it's irresponsible too meet up with the better half, thats how kids come too be:rolleyes:

[Merv121]

welcome merv, you made the same transition as me. Cbr 125 (05) to sv650, although mines an older model (01 S) thats restricted to 33bhp (for another year now).

thanks chez for that, finally get to pick it up on saturday super excited, my cbr was an 07 but it had problems with pretty much everything apart from the engine and gearbox, lol! hope to see you on some rideouts if i can manage to get out on some :) still restricted till march 2014 :)

Easy fellas this is all getting a bit unpleasant, @Merv pick what useful info you can from the wreckage of this thread.

I would post my opinion, but I don't feel like getting typed at.:(

thanks thunder i have looked through and the road stuff ive looked at, and ive taken in quite a lot and have decided to stay with manufacturer's recemendations, as i dont pick the new bike up on saturday i have no idea how it will feel, and as for track psi's.. i am taking them in as i do actually work at donington park as a track marshall (trackdays not race weekends so the paid work :P) but with it being such an uneven circuit and having so many grip issues with the cbr its put me off trackdays till i can get confident again!


-------

and also thanks to everyone in the thread whos shared the opinions its helped quite a lot so far!

[Lozzo]

I don't tend to follow this school of thought.

<Snip lots of relevant stuff>

I tend to agree. I play about with pressures and different makes of tyre on certain bikes will require a slight change. It does depend on the use you're putting the bike to as well. On road I'm running at the recommended 32 front and 36 rear on my Versys on the current tyres*, which is the same as my CBR600 is meant to be run at on road. On track my CBR is running 29 rear and 31 front and handles lovely - any change to those pressures and I notice a deterioration in handling on both bikes.

*I have had to run 30 34 on Avo Vipers and 34 38 on Pirelli Angels on the Versys.

[chezvegas85]

thanks chez for that, finally get to pick it up on saturday super excited, my cbr was an 07 but it had problems with pretty much everything apart from the engine and gearbox, lol! hope to see you on some rideouts if i can manage to get out on some :) still restricted till march 2014 :)

Mine put up with some right abuse and never really complained bless it, i've not been on one yet, prob be the AR if i can convince the mrs i should be allowed to go to it when its organised

[monkey]

Here's a spanner for the works:

Shouldn't one ask the tyre manufacturers they're suggested starting point for their particular tyres on a particular bike?

[johnnyrod]

More relelvant than the bike's manual, but then they'd all say 36/42 because it's safe-r i.e. no dinged rims/snakebite punctures and better high speed stability. If we followed the mfr's instructions we wouldn't do 90% of the things we do.

[NTECUK]

So if pressures set in stone then by that Logic,bestdon't touch thoes suspension setting then.
Its all part of that system after all.
Given some tyres have stiffer sidwalls compounds how can you expect it to be "just right".
OK dont go silly adjustments . But as said 2 psi either way could rep rewards.
Live long and prosper?

[speedyandypandy]

So if pressures set in stone then by that Logic,bestdon't touch thoes suspension setting then.

I love how some people just make up things as they go..... anything else in the fairybook of wonders?

The suspension settings isn't set in stone, atleast not in my manual, it actually gives advice when to change settings, same with the gixer manual. Don't know what the CB or GS manual says.

Ever heard the saying: "He who would learn to fly one day must first learn to stand and walk and run and climb and dance; one cannot fly into flying"

My first advice to merv was to change around the suspension, but somehow the focus has become tyre pressures and personal opinions based on dubious skill levels and personal prefrences.
Suspension set up first(with a known tyre pressure that we all know works, hence 33/36), tyre pressures second, and for normal riding 33/36 is perfect midway between all styles of riding, and getting to know the bike while finding you preffered suspension setting. Some riders gets the first part nailed after a month, some riders don't have a clue even after 20 years.

Maybe it was wrong to say it's set in stone, playing with the tyre pressures is ok to do, if you know what your doing, but not if you only think you know what you are doing, 95% of people asked where they find themselfs as a driver said above avarage.


For a person going from a 125 to a sv starting out with loads of information with as many different tyre pressures as there are different riders is like dropping a person in the middle of a great forrest without a compass and expect him to find north. Better someone show him a easy route to begin with and let him evolve at his own pace.

[NTECUK]

Yes agree with that.
When I first got the bike set every thing as per Mr suzuki and later Mr 'prilia .
Then the tyres were the last thing .
But like you say if his inexperienced best get a helping hand .
Best performance mod I did on the RSV easy to get the suspension sorted out .