YonathanZ

Hi,

I have a 20 inch, electric, folding, commute bike. It has Kenda Kwest (K193) 20 x 1.5 tyres. On the sidewalls of the tyres, it says minimum PSI is 40 and maximum is 65, but on Kenda's website it says that max PSI is 100. I guess it's the specifications on the tyres' sidwalls that I should follow?

Another thing. I have a hand pump with no gauge. Can I use a car compressor to inflate the tyres of my bike?

dabac

I'd stick with the sidewall value.
If your tubes have the right type of valve, Schraeder.you can indeed use a car pump.

YonathanZ

Yes, they have that common valve type. I'll give the car pump a try tomorrow. Thanks!

fietsbob

There are BMX stunt tires with higher pressure casings ,, IDK which Product you have . from words Here.

JanMM

Kenda Kwests are common on various recumbents and come in 100- and 65 psi versions. Both are considered rugged/serviceable but on the heavy side.

ThermionicScott 

I would buy a floor pump with a gauge as soon as finances allow. They're well worth the $15.

Andrew R Stewart 

It's pretty common to over pressure tires on all sorts of bikes and all sizes. Generally 10% more is within reason without much concern. This is assuming all is in good order. First is the tires' fit to the rims, even and consistently seated. Next is the rim having a proper hook edge to best grip the tires with. The tire casings and tread shouldn't be old, cracked or showing exposed threads.

The Kwests are pretty basic tires. Not too supple or "fast" (I hesitate to use that word...) but pretty durable. JanMM is correct that in some sizes they are available in either a 65 or a 100 PSI version, not sure in the size you have.

But the elephant in the room is why do you want higher tire pressure? Do you want to go faster? Are you getting pinch flats often? Don't blindly buy into the idea that a tire with higher pressure is automatically going to be faster. Generally the higher the pressure the less the traction so cornering, rain riding and such might actually be worse.

Lastly this type of bike isn't usually designed with speed as part of it's criteria. The electric assist is generally considered to be there to make it easier to pedal at any speed below the governed max. Andy.

YonathanZ

I ended up pumping air at the gas station. I set the pressure to 58 PSI. It does seem to roll more easily now, but the ride is very bumpy anywhere but on the road.

Andrew R Stewart, is there a tyre that will better fit my needs, in your opinion? One that is a good balance between comfort and speed... I read recommendations about the Schwalbe Big Apple. Are they "better" than the Kwest?

davidad

Tire pressure is a function of vehicle weight and tire width. https://www.bikequarterly.com/images/BQTireDrop.pdf

Andrew R Stewart 

I don't track the offerings for the 406mm diameter. But by looking at a number of tire specs and understanding a bit about tire construction one can make some assumptions, actual use is the only way to confirm these assumptions.

Look at the weight for the same ISO dimensions, lighter usually means a thinner rubber tread cap and/or a thinner casing. Look at thread count, higher usually means a thinner casing belt which will be more supple. A lighter and more supple tire is usually more comfortable for the same pressure, often will roll with less friction losses, often have greater traction (for the same tread pattern) but also often will have less durability to glass or road conditions. Adding belts/layers of puncture resistant materials (poly plastics/Kevlar) only adds weight and casing stiffness, other then the flat protection improvement the tire will roll slower and feel harsher.

To some these aspects are lost or so minimal that they won't consider them important. Others will place a high priority on flat protection or load capacity or some other aspect. Each of us should find our own sweet spot since all the possible tires will work well enough within their design intentions.

My preference is for a light and thin tread cap and casing. I like a rounded profile (VS a flat or square shape) with little tread pattern. Since I don't get many flats and can deal with those that I do get easily (and I'm always prepared) I tend to use tires with little or no penetration barrier layers. I chose a width that is a bit more then many and therefore don't need max pressures. I get a smooth and grippy ride this way. Andy.

1 Miyata Biker

I'd stick with the Minimum/Maximum air pressure located on the sidewall of the tires. You can probably exceed that by 10% if you so desire. I would imagine the tubes are schrader valve type, so a hand pump or air compressor should work fine with the correct connection. Be careful with the compressed air, the 20" tubes will fill quickly. A regular vehicle air gauge will usually check tires in the 0 to 65 lbs. range. Otherwise, just make sure the tire feels somewhat firm when you squeeze it if you have no gauge.