New Tyres - Necessary To Inflate To Manu. Recommended PSI??

[woodbine]

I ride a mid 80s British Eagle MTB. The old slick/road tyres I had were Tioga city slickers, which I used to inflate to around 65 PSI rear and 60 front which was within manufacturer's recommended pressures. All was well.

I had to replace these and bought a pair of Schwalbe City Jets 26 x 1.5". On the sidewall, it says to "inflate to 85 PSI". I thought this was a bit extreme, so inflated to approx. 75.

Bearing in mind it's an old bike with no suspension, the ride is now very hard and uncomfortable. Every slight bump and pothole is transmitted through the frame and the bike is now uncomfortable to ride and rattles along.

If I reduce the pressures further below the maker's recommended pressure to around what I was using in the old tyres - will this affect the tyres? Will it cause them to wear quicker or be damaged? Are all slick tyres like this these days - needing very high pressures? Do others ignore the maker's pressure recommendations? Are there other slick MTB tyres that would be better for my needs?

When I was growing up, I can't think that we would ever have pumped up bike tyres to such high pressures. I'm sure that a traditional, frame-mounted tubular tyre pump would have been incapable of inflating a tyre to anything like 85 PSI. Why are such high pressures needed now?

 

[jimo746]

Re:

Use whatever tyre pressure you like, manufacturers often put on the Maximum recommended tyre pressure on the sidewall of the tyre, a bit like a speed limit its the Maximum pressure, not a target, so there's no issues running 50psi in a tyre with a maximum recommended pressure of 65psi.

I had the same Schwalbe city jet tyres and used 65psi in them, still have good rolling resistance but soaked up a few more bumps for a more comfortable ride.

Other factors affect the pressure you'll find best for you, like the size of the tyre (26x1.5 vs 26x1.9 etc) and the width of the rim it's mounted on, so there's no real hard and fast rule, try different pressures and find out what suits you best.

All I would say is don't exceed the Maximum recommended pressure, and don't go stupidly low with the pressure as you'll risk the tyre potentially rolling off the rim on corners (plus you'll find the tyres won't roll as quickly on the road with too little air in them).

What size were the old Tioga city slicker tyres you had? Same as the new ones? Or are the new ones a bit narrower?

 

[woodbine]

Thanks Jimo746, you've set my mind at rest. I have replaced with same size as old tyres - 26 x 1.5" on old Rigida CTX50 alloy rims.

What has thrown me is the difference in instructions between the old and new tyres. The old tyres had instructions on them to inflate BETWEEN 60 and 75 PSI or there abouts (can't remember exact figures). However, new Schwalbes say "INFLATE TO 85 PSI" - which sounds like a mandatory figure, not a maximum. Perhaps I'm understanding it wrong and they really mean UP to 85PSI.

Rode out on the new rubber for the first time last night to the pub - only a 6 mile round trip. Needed those pints when I got there. Definitely shaken, not stirred!

 

[cce]

City jets have all the feel of a length of old hosepipe.

 

[Raging_Bulls]

Re:

hmm

Looking at my own 1.95s, the sidewalls clearly say "inflate to min 2.0 bar (30psi) - Max 4.5 bar (65 psi)". Perhaps it's different on the 1.5" version.


Here's the specs of the 2016 version :



I'd use common sense. Anything between 55 and 80 PSI should be good.



@ cce : no such issues here, and I use them both on and off roads.

 

[woodbine]

City jets have all the feel of a length of old hosepipe.

Are they not a good choice of road tyre? What slicks would you recommend for a better ride?

Thanks to raging_bulls for the info.

 

[cce]

Re:

It's not a market I know well. City jet is an urban commuter tyre. They have superb puncture protection, but they suck all of the fun out of riding for me.

 

[focomat 1c]

Re:

I fitted some City Jets to my Muddy Fox several years ago. The bike is used to explore local tracks and trails etc on a variety of surfaces, but
mostly tarmac

I chose this tyre because of its puncture resistance and very low rolling resistance. To achieve low rolling resistance the tyre
has to be capable of withstanding high internal pressures in order to minimize both sidewall deflection and the area of the contact patch.

Similarly the tread compound in contact with the road needs to be as hard as possible while at the same time retaining good gripping ability and low wear.

I run my tyres at about 60psi and find them ideal for my purposes. As with many things you have to make a compromise, in this case between
comfort, grip and ease of pedaling

If your bike 'rattles' with the new tyres perhaps it is time for a few minor adjustments ?

 

[widowmaker]

Re:

I ran Cityjet 1.5's on my Univega for a good few years, I had them around 60, they were spot on for me. On tarmac bridleways and suchlike, never had and punctures.

 

[mattr]

Most of my mtb tyres aren't even inflated to the manufacturers minimum pressure (if there is one).

And the high pressure = low rolling resistance has been fairly thoroughly debunked over the last 10 years. Unless you are running on a perfectly smooth surface. Like a velodrome. Anything real world, dropping pressure by 15-20% will give you less rolling resistance as the tyre conforms better to the road surface. Too low and everything gets worse again. Squirmy tyres, lots of drag and so on.

This all gets very contentious as people think having their teeth rattled means they are going fast.

Also gets stuffed up by crap tyres that have all the characteristics of a length of hose........

If you want some really nice, fast, grippy tyres in city jet sizes, try compass. Not cheap, but very very good.