Tyre direction and pressure

shephga

shephga

shephga

Associate
Joined
27 Feb 2003
Posts
1,159
Hi,

I'm lucky enough to have a new job closer to home, so close I can bike with 10-15mins and I've not regulary cycled for 22 years until now. My bike is a 3+ year old Carrera Vulcan, I've read up and found the knobbly's weren't efficient for my route which is mainly road/rough pavement. I've bought some Schwable City Jets and fitted them (was a pain) and now have two questions.

1 - Max tyre pressure is 85psi, I've pumped them up to 60psi and they're rock hard. I'm a 15 stone 9lb bloke with a daily backpack load of an additional stone or so. I want comfort as I dont want to put myself off biking from a sore arse etc. Should I really go to max pressure ?

2 - I'm embarrassed to say the rear tyre is on wrong, the drive arrow is pointing in the wrong direction. The tyre was an arse to put on, can I get away with leaving as is ? The tyres are slick.

Thanks in advance
 
1. How do the tyres look when you are on the bike with your backpack, still pumped up enough?

2. If a tyre is designed to be put on in a certain direction, I would say you should have it fitted correctly. Otherwise, you won't get the intended grip from the tyre, e.g. under braking in the rain.
 
I think you should google the word "Maximum" :p
Below max is fine, above max is not fine.

I wouldnt worry too much about having a slick tyre on backwards, just remember to turn it around next time you have it for for a puncture of whatever.
 
Well, if your arse hurts after riding that's got nothing to do with tyre pressure, most likely it's to do with your saddle height, shape or otherwise bike fit, or the clothes you're wearing.

Pressure wise since they're quite wide tyres still i don't think you need to go as high as that, i plugged some rough numbers into the 15% drop calculator which say 45psi for the front and 67psi for the rear, play around with it and see what feels right to you.

Googled the tyre and it still has treads, i would definitely recommend putting it on the right way. Pro tip: put it so that the writing on the tyre is next to your valve hole so you can easily find it.
 
Cheers all, I've checked the manufacturers website, the drive arrows indicate optimum direction for reduced rolling resistance, I'll wait til for puncture before I change the tyre direction. With regard to tyre pressure, many of the tyre reviews on amazon and other cycling pages say to get the full benefit you have to take the tyre up to 85 psi which just seems crazy, especially with factors such as rider weight, what I'm carrying and I've just read even rims (I think this means the wheels ??) have pressure ratings too. I'll stick at 60 and see how they feel tomorrow, the tyres keep their shape with me mounted so I think it should be ok. I had a bad experience with a petrol station air pump and my grifter back in the 80's, I basically inflated the tyres til they were like moonbuggy wheels, felt great for the first few feet until the tyres popped...
 
you might have a max wheel rim pressure too so check 60psi is'nt too much for the rim, prolly be ok though.

and yep did the same to my chopper in 81? woohoo the tyre is sooo hard!...BOOOOM oh no hehe
 
Yeah there is no need to run them as high as 85 PSI. I did this with my hybrid which will have similar width tyres to what you've just fitted and it was horrible to ride as it rattled over every imperfection in the road.

From what you've said I'd start off at around 50 PSI in the front and 65 PSI in the rear.

The recommendations to run them at max PSI come from the misconception that highest pressure = lowest rolling resistance = highest speed. What you need the tyre to do is deform slightly under you to keep you in contact with the road rather than skipping over it.
 
You must log in or register to reply here.
Back
Top Bottom