Tyre pressures for a lightweight?

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

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.

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]

Originally Posted by 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.

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.

Originally Posted by jambo

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.

Originally Posted by NTECUK

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.

Originally Posted by jambo

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.

Originally Posted by 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

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

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]

Originally Posted by speedyandypandy

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

Originally Posted by speedyandypandy

tyre pressure is normally the thing thats set in stone

Originally Posted by jambo

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) 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.