Changing Pressure on Fat Tire Bikes With Slime

Hikertrash

Member
I have a fat tire bike (20" x 4") and usually have the tires inflated to 20lbs. on roads around the house. I plan on doing some trail riding and will probably drop the pressure to 15lbs. If I were on the beach or in snow, I could see dropping the pressure even further.

If I add Slime or another tube sealant will I run into problems inflating, then deflating, the tires?
 

Tars Tarkas

Well-Known Member
No, absolutely not! I have Slime in 26 x 4s and run pressures from 8 to 20 psi. I tend to overdose my tires (put in a little more Slime then they recommend.)

TT
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Yes, I run a little more than "suggested" as well.

As far as related problems when changing pressure downward, I would say it can be sloppy if you aren't expecting any Slime to come out when releasing air pressure. I mean it's no disaster, but you might want to be prepared with a damp rag or paper towel. If you do this with the valve core at 12 o'clock the Slime contained in the valve stem is going to come out before any air does. The preferred position might be at 3 or 9 o'clock with a slight pause to allow the Slime to drain from the valve stem. I would NOT try releasing air with the stem at 6 o'clock!
 

Handlebars

Well-Known Member
Region
Canada
I have a fat tire bike (20" x 4") and usually have the tires inflated to 20lbs. on roads around the house. I plan on doing some trail riding and will probably drop the pressure to 15lbs. If I were on the beach or in snow, I could see dropping the pressure even further.

If I add Slime or another tube sealant will I run into problems inflating, then deflating, the tires?
I squirt water into the valve to help get the slime out before attempting to use the pump. Squirt water in, let the slime in the valve stem splutter out.
 

Fredman

Member
My concern is for the pressure testing gauge when checking tire pressures. Surely when I connect it to the valve some slime will get into the gauge...and that won't be good for the gauge?
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I've not had an issue with that to date - maybe 3 years now while maintaining 2 bikes. I will admit that some Slime just about has to get into it.

Worst case, I'll get another inexpensive gauge when/if it quits.

Going to take a better reason than that to even consider stopping the Slime treatment here....
 

Fredman

Member
Thanks. That's good to know. We're getting our bikes in a few days and I will be adding slime.
Another question plz. Do you set the valve in the 12 o'clock position when checking pressures with the gauge?
 

Handlebars

Well-Known Member
Region
Canada
My concern is for the pressure testing gauge when checking tire pressures. Surely when I connect it to the valve some slime will get into the gauge...and that won't be good for the gauge?
Some gets in the pump every time I use it. I guess it's not critical because the pump blows air out and since I use water to clean the tube valve out first, it's already diluted. The pump meter does seem affected a bit, though, then it acts OK.
 

Tars Tarkas

Well-Known Member
Position might matter. I'd think on the downside of between 2 and 10 would be fine. 12:00 means the Slime could theoretically flow down the valve stem and into the gauge. But I don't pay much attention and have never had a problem.

TT
 

Handlebars

Well-Known Member
Region
Canada
Wouldn't 4 or 8 o'clock be optimum?
I have tried different ways to avoid the Slime. For some time I've been positioning the valve at 12:00 for a while, hoping that the Slime then goes downward, then turn it to 8:00 and wait a while, hoping the valve stem empties, but always the same result - Slimed. I never have tried 6:00, for obvious theoretical reasons.
 

Handlebars

Well-Known Member
Region
Canada
Yes, I run a little more than "suggested" as well.

As far as related problems when changing pressure downward, I would say it can be sloppy if you aren't expecting any Slime to come out when releasing air pressure. I mean it's no disaster, but you might want to be prepared with a damp rag or paper towel. If you do this with the valve core at 12 o'clock the Slime contained in the valve stem is going to come out before any air does. The preferred position might be at 3 or 9 o'clock with a slight pause to allow the Slime to drain from the valve stem. I would NOT try releasing air with the stem at 6 o'clock!
I never try to use the pump without first clearing the valve stem. Today I'm going to try releasing air at 12:00 position after waiting a while, to see if that helps it clear better.
 

Gionnirocket

Well-Known Member
I've found that adding a little bit of air with a compressor with the valve at 8 to 10 o'clock works best for me to clear the valve of slime.
I have a digital pressure gauge and it hasn't had any problems so far.
I have had slime foul a valve even after waiting 15 minutes for it to clear at the same position.
I would avoid messing with air pressure out on the road unless absolutely necessary.
 

theemartymac

Active Member
I never try to use the pump without first clearing the valve stem. Today I'm going to try releasing air at 12:00 position after waiting a while, to see if that helps it clear better.
I think you would be better off taking a quick ride at speed, then immediately adjusting when you stop. The centrifugal force will cause the slime to migrate to the outside (tread side), and even the increased viscosity and surface tension wouldn't prevent that. Just letting the bike sit won't move a thin layer of slime very well, as it's sticky by nature and there is no real capillary action like water that would otherwise 'pull' the slime down off the upper surfaces.

Just talking out my ass though, so somebody test it and report back, lol ;-)
 

Gionnirocket

Well-Known Member
I think you would be better off taking a quick ride at speed, then immediately adjusting when you stop. The centrifugal force will cause the slime to migrate to the outside (tread side), and even the increased viscosity and surface tension wouldn't prevent that. Just letting the bike sit won't move a thin layer of slime very well, as it's sticky by nature and there is no real capillary action like water that would otherwise 'pull' the slime down off the upper surfaces.

Just talking out my ass though, so somebody test it and report back, lol ;-)


I had tried that to let some air out while on the road. I won't be doing that again.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I use tyre liners. What’s the cons and pros to tyre liners vs slime? I am new to cycling.
For the areas I ride, I've become so confident in the Slime, it's hard for me to justify the liners. Between the wife and I, I'm averaging less than 1 flat a year (going to go look for a piece of wood to knock on here). Even if I were to install liners, I'd STILL use the Slime.
 

Terry777

Active Member
For the areas I ride, I've become so confident in the Slime, it's hard for me to justify the liners. Between the wife and I, I'm averaging less than 1 flat a year (going to go look for a piece of wood to knock on here). Even if I were to install liners, I'd STILL use the Slime.
Oh man! I hate when you do that. You're regretting saying something as the last words are coming out.

Say.... "Hairy wood is the best wood" then a couple of chaps on your head usually does the trick! LOL

I hope i have the same results! I dunno why i went with tyre liners. Now i check it out it would have been a lot less expensive and so much easier to use!
 

Gionnirocket

Well-Known Member
Oh man! I hate when you do that. You're regretting saying something as the last words are coming out.

Say.... "Hairy wood is the best wood" then a couple of chaps on your head usually does the trick! LOL

I hope i have the same results! I dunno why i went with tyre liners. Now i check it out it would have been a lot less expensive and so much easier to use!
I use both and too be honest I'm not sure that I would use slime again. Though tire pressure rarely varies, it is a pain to check.
 
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