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Anthony2 06-26-11 04:02 PM

How Much to Inflate Tires
 
My tire has the following information on it:

665kpa, 6.7 bar, 95 PSI

So I have two questions:

1.) I'm a heavier dude...260 lbs. Is it better to inflate the tire to 95 PSI? I don't know why, but for some reason I've been riding on 80 PSI. The rides been good, but 1) I wonder if it could be better and 2) if I'm causing or may cause damage to the wheel by under-inflating.

2.) Just read online that it's better to use less pressure on the front wheel (so 90 PSI?) because it'll give you "better traction?" Is there any truth to this? Should I go with 95 in the back and 90 in the front? Or stick to what I've been using? About 80 front, 80 back?

Any comments/suggestions would be greatly appreciated.

Thanks!

Nightshade 06-26-11 04:30 PM

Under inflation can ,and will, cause "pinch" flats.

Best plan is to pump your tires hard as a rock for a easier pedaling (less rolling resistance) and no pinch flats.

Scrockern8r 06-26-11 04:36 PM

What type of wheels and tires you have makes a difference.
The max listed pressure of 95psi tells me the tires are larger (>32mm wide) and may be for an older type of wheel.
Old steel type 'non-clincher' wheels are lower pressure ~90psi max. Newer clincher types can be run with what ever the max on the tire may be.
I run about 250lbs as well, and I am very happy with using tire drop for my pressures. Tire wear seems appropriate, and the ride feels good to me.
Riding an old road bike with clinchers, my pressures are 70/100 front/rear.
- The first set of tires were installed on the older wheels and run at ~80psi. I ran the rear bald in about 1700 miles.
- This second set on the new rims with the tire drop pressures; just starting to show wear on the rear at 1000 miles.

As for pinch flats, I think it is all about riding style. The older 27x1&1/4 wheels and the fairly big tires were plenty for me and I never pinch flatted while running at lower pressures like what you currently run.

FBinNY 06-26-11 04:46 PM

It's more than a matter of inflation, it's also a matter of tire cross section, especially at your weight.

Just as you wouldn't put sports car tires on a truck, you shouldn't be riding on tires made for someone weighing 160 pounds, regardless of pressure.

Here's a short guide to tire pressure for a variety of weights and cross- sections. Don't take the numbers as gospel, but as a starting place for finding the best pressure for your needs and tastes.

I personally don't like to ride hyper inflated tires because cornering traction suffers too much, so I look for tires that will support my weight at 90-105psi.

On my commuter, I'm riding fairly wide mtb (smooth tread) tires at much lower pressures (50-65psi) giving me more freedom to not woeey about the roads with no meaningful increase in rolling resistance.

Retro Grouch 06-26-11 05:45 PM

Are you getting frequent pinch flats?

The problem with under inflation is pinch flats, the kind with two parallel slits in your inner tube like a snake bit it. If that's not happening to you at 80 psi you're not damaging the rim so I wouldn't worry.

At your weight you might want to consider experimenting with more air pressure at least in your rear tire. It'll probably roll a little more easily at the expense of ride quality. Try pumping your rear tire up to 95 psi. If you don't like it you can always let the air back out.

Over doing air pressure is also bad. It actually makes you work harder to ride the same speed and negatively affects both handling and ride quality.

achoo 06-26-11 06:31 PM

More air in your tires will not necessarily reduce your rolling resistance, especially on rougher surfaces.

Feel and hear that buzz? That's energy that has to come from somewhere. The only source of energy on a bike is your legs, so that buzz will manifest itself as increased rolling resistance.

Besides, rolling resistance is pretty minimal to start with on even halfway decent tires.

JanMM 06-26-11 06:35 PM

At your current weight, you may be better served by wider rather than thinner tires. You don't say what tires you are using.
The Tire Drop article reference previously can be a useful tool in figuring out optimal tire pressures.

Anthony2 06-26-11 07:10 PM

Appreciate the help, guys. Thanks.


Originally Posted by Scrockern8r (Post 12843229)
What type of wheels and tires you have makes a difference.


Originally Posted by JanMM (Post 12843599)
You don't say what tires you are using.

TIRES: Pasela-TG K tire 700x32c

LINK:

http://www.outsideoutfitters.com/p-3...700c-tire.aspx

RIM: Dyad 29"/700c rim 36h - black

LINK:

http://www.outsideoutfitters.com/p-4...-700c-rim.aspx

So any differing opinions now that I've provided the rim and tire information above?


Originally Posted by FBinNY (Post 12843254)
Just as you wouldn't put sports car tires on a truck, you shouldn't be riding on tires made for someone weighing 160 pounds, regardless of pressure.

Hey, FB. Had my wheels built last year - you actually helped me with the a couple things regarding spokes. :) Anyway, the wheels (thankfully) are great. Please check above - I've provided more information.


Originally Posted by Retro Grouch (Post 12843440)
Are you getting frequent pinch flats?

Thankfully, nope. Just trying to use some precaution.


Originally Posted by achoo (Post 12843580)
...

Thanks!

pdlamb 06-27-11 08:14 AM


Originally Posted by Anthony2 (Post 12843732)
TIRES: Pasela-TG K tire 700x32c

RIM: Dyad 29"/700c rim 36h - black

I'm about your weight, and ride similar wheels. I like riding with the tires around 85 psi, but I'll usually inflate to 90-95 psi. That's because I'm too lazy to check every day before I head in to work, so a week's riding often leaves me with only 75 psi, which is getting low. For a big ride, say a century, I'll aim for 85-90.

jayp410 06-27-11 09:00 AM


Originally Posted by Anthony2 (Post 12843153)
2.) Just read online that it's better to use less pressure on the front wheel (so 90 PSI?) because it'll give you "better traction?" Is there any truth to this? Should I go with 95 in the back and 90 in the front? Or stick to what I've been using? About 80 front, 80 back?

The rear wheel typically has to support about 60% of your weight. (You could put a scale under it to measure, even though the load does shift a little on the road) so in general the back requires more pressure than the front. Less pressure in the front gives a smoother / less jarring ride especially in the handlebars region.

Al1943 06-27-11 12:41 PM

If I were you with those tires I'd go 100 psi in the back and 95 psi in the front. And pump them up before each ride.

Anthony2 06-27-11 06:38 PM


Originally Posted by pdlamb (Post 12845537)
I'm about your weight, and ride similar wheels. I like riding with the tires around 85 psi, but I'll usually inflate to 90-95 psi.

I've done 80 PSI since last summer - I'll need a few more rides, I think, before I can figure out which one numbers to stick with.


Originally Posted by jayp410 (Post 12845758)
The rear wheel typically has to support about 60% of your weight. (You could put a scale under it to measure, even though the load does shift a little on the road) so in general the back requires more pressure than the front. Less pressure in the front gives a smoother / less jarring ride especially in the handlebars region.

Cool, thanks for the tips. I do, in fact, want a smooth ride - I assume everybody does? 95/90 felt a bit stiff - not sure if it was in my mind or what, so I guess I'll do as mentioned above and play around with the pressure to see what works best.


Originally Posted by Al1943 (Post 12846822)
If I were you with those tires I'd go 100 psi in the back and 95 psi in the front. And pump them up before each ride.

Thanks!


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