939 Tyre Pressure

This is the one big question. The booklet says one thing and the Frame another (at least for the 939 SP).
Reflecting on it I think it is because of the Super Corsa SP where they recommend 23 for the Front and 21 for the rear!
My "naive" thinking (maybe some member can say if I am ok thinking this) is that with 23 on the front it would not scrub that much and would last longer (as the SP has not much thread on the front) where the rear has more so lower will give more grip as it would scrub more and will have both lasting similar Kms....

Before on a 821 I had Michelins and I was running 23 23 on both as recommend by dealer despite manual saying 25 29 rear front.

 

I run 30 front and 32 rear. Handles amazingly well.

I've tried lower pressures but it doesn't resolve the high speed head shakes so went back to 30psi.

 

By high speed you mean ? Sorry to ask just want to know because I can ride in Germany and high for me is 250 km/h on autobahn or ok average 170-85 ....

 

About 90mph+ it can shake on full acceleration right up to 140.

It isn't bad, I kind of enjoy it if I'm honest.

 

So if I understand by raising the pressure the tires keep their shape better and that helps on reducing head shake right? Provided suspension settings same .

 

The only real way to cure head shake on a bike like the Hyper is to buy a steering damper.

I haven't had a nasty tank slapper as of yet so I'm probably not going to bother but it's early days.

For the record, my bike (2016 939 SP) states 33psi front and 30psi rear on the frame. To be honest I've not bothered to check what the manual says so it could well state something completely different.

At present, I'm running 30psi front and 27psi rear which feels pretty spot on with standard suspension settings once they're up to temp. SC's can be run with significantly less pressure than that but they'd really need a very warm day or a short stint on warmers followed by a handful of abuse to keep them taught at track pressures when you're riding on the road. Simply put: it's not recommended.

That being said, I usually ride with Michelins so I can't say for sure that lower pressures are a bad idea with SC's.

The right pressure for you is more about how and where you ride than it is about anything else...

If you bimble around you may need a little more pressure to make up for the colder tyre temps. On the flipside, if you work the bike pretty hard you may well need to drop the pressures to keep the operating pressure in the right kind of ball park.

Bizarrely, the exact opposite can also apply as some people don't like the knife edge feeling of properly inflated tyres so will naturally run with very low pressures regardless of speed/temp. Not recommended but each to their own I guess.

Just remember that the real reason to get the pressure right is to ensure that the tyre moves and flexes as much or as little as the OEM intended it to when it's up at operating temperature.

Tyre wear is a good indicator of whether or not you've got your pressures right but that's another long story that you'd be better off Googling.

TL;DR: pressures are very much individual to the rider and setup of the bike. Stick to roughly what the manufacturers recommend and you won't go far wrong.

 

Thanks for the info.
For me the pressures on the frame work well. I do mountain roads mainly so I work out well the SC tires. I am on the edge of the rear already rubber looks well worn etc. I feel there is good grip never had a scare with these tires I like them but as any Pirellis I am sure they will start to behave different as the rubber wears down the marks.

For that reason I will mount Metzeler M7RR as I have them in my Naked and I like very much their feel. Hope they won't mess up the flicking of the hyper will see. But lean angle I will certainly win because they are rounder.

 

How strange that my USA 939 SP says 36/36 on the frame and in the manual? Same as my wifes 2015 Hyperstrada.

 

Weird. What tyres did it come with?

 

Pirelli Super Corsa's. Same as Euro? Very odd that Ducati would spec different tire pressure for Euro vs USA?

 

Also looked at the Pirelli website and it says 33/36 for the 2016 SP.

What a mystery. The Pirelli site sounds good to me. I think I will go with the 33/36.

 

Very strange. The UK spec tyres are Super Corsa SP's but I can't imagine they'd ship US bikes with different rubber.

Are you in California by any chance? Could be another funky tree hugging thing as higher pressure equals less rolling resistance and therefore better fuel economy. Beyond that, I'm stumped!

EDIT: just noticed that you're from New Hampshire.

 

Yep. Same tires here in the USA. I will have to ask my Dealer to send along the question, of why the UK spec for pressure is different, to the Ducati tech folks.

 

My pressures (939sp) had dropped off a bit recently - I usually run whats on the frame, on SPs. Since it got cold/bikes and the bike's been stood for a while so I rode it carefully up to the garage a mile away to top them up. Going round corners the bike felt horrible - the front really heavy - almost clunking to the stops once turned in on a slight lean. Horrible. Front had 25 psi on their guage so not that low at all for the loss in handling. Was very surprised to say the least.

 

Would it be that your rear is already squared ?

 

It's not thaaaaat bad. Totally went away once back up to pressure.

 

Mine starts to show the treat markers (those that say less than 2mm left) but also after only some few kms going to work on city and 60 km/h routes around and they start again showing signs of slight squaring. One can feel it because on a slight lean the front start to close and stands it up (on speeds 40 km/h< ).

I was to wait and get new ones on spring but if we have a sweet winter I would want to ride it and therefore I need the new set. Now to choose Diablo Rosso III or M7RR. I know the M7's and love them the other is to test them.

 

Just picked up my SP today and the manual says 2.5 bar front and rear for Super Corsa solo use. That is 37.5 psi front and rear (Bar x 15) and different to what has been said above. The frame says 33 psi front and 30 psi rear, nice work Ducati! I am old fashioned enough and raced enough to want more pressure in the rear than the front on the road and to preserve tyres. Am I wrong and is the low pressure on the rear all about drive on the track but on the road? I will do the odd track day so advice for that would be appreciated. 34 front 36 rear will get my vote until I know different + or - 2 psi.

 

Now having ridden on our bumpy hills roads and seeing Pirelli's official recommendations of F 29-32 psi and R 23-26 cold measurement for road use, maybe I need to rethink? Any feedback from anyone for this newbie to a Hypermotard 939?