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Fat tire speeds

Posted: Mar 13 2019 6:38am
by epower-1
Does any one have any info on what kind of speeds a fat tire is rated for
thankx

Re: Fat tire speeds

Posted: Mar 13 2019 10:26am
by kcuf
dunno any rating

25 30 mph is about as fast will cruise on 4 or 5 inch tires

have touched 35 downhill and all seemed fine

fairly noisy at higher speeds

Re: Fat tire speeds

Posted: Mar 13 2019 12:07pm
by epower-1
Thanks for the info
I have some 20 inch 4 inch wide fat tire slicks running 20 psi mounted on a EEB endure bike
that will hit 40 mph I am wondering if they will hold up or blow out and I crash

Re: Fat tire speeds

Posted: Mar 13 2019 12:49pm
by Chalo
epower-1 wrote:
Mar 13 2019 12:07pm
Thanks for the info
I have some 20 inch 4 inch wide fat tire slicks running 20 psi mounted on a EEB endure bike
that will hit 40 mph I am wondering if they will hold up or blow out and I crash
The tires can take the speed. Whether you have a failure at such speed is more dependent on the bike's mechanical condition and the state of the wheels.

Bicycles were exceeding 40mph long before goofy suitcase e-bikes (or any e-bikes) showed up.

Re: Fat tire speeds

Posted: Mar 14 2019 4:35am
by epower-1
Thanks for the feed back any and all helps in the land of confusion
I know bikes have been going 40 mph down hills forever
I was wondering about the new fat tires and how they would hold up to speed
thank you

Re: Fat tire speeds

Posted: Mar 14 2019 6:01am
by dogman dan
Not much speed, if you have them inflated as soft as they were intended to run. But 20 psi is fairly hard, and should handle " normal bike speeds" By that I mean up to about 30 mph. I'm not sure what happens if you inflate a fat tire to 60 psi, where I'd want tire pressure for 40 mph.

Though a good bike can handle 60 mph, that does not mean your particular frame, carrying a heavy battery and perhaps a heavy DD wheel, will like it. I'll do 60 mph downhill anytime on my 83 centurion road bike. No motor kit unbalancing it, and its one of the best steel road frames ever made.

I think I'd want to keep it below 25 mph on a cheap ass mongoose fat bike. IMO the difference is not tires, but the frame stiffness, and how its weighted, that determines the speed the thing starts to go tank slapper on you. I've seen bike shaped object MTB's start to speed wobble at 15 mph. So if your fat bike has a great frame, its one thing. If its a bike shaped object with fat tires, another. Weak frames will show up easy, they bend side to side with every hard pedal stroke, visibly.

Re: Fat tire speeds

Posted: Mar 14 2019 6:07am
by LeftieBiker
I'm not sure what happens if you inflate a fat tire to 60 psi, where I'd want tire pressure for 40 mph.
Due to incorrect instructions in the "manual" I inflated my new 20 x 4 fat tire folder to 50psi. I didn't get it moving very fast, but even at low speeds it was a hard, noisy, bouncy ride. They seem ok after being lowered to well below 30psi.

Re: Fat tire speeds

Posted: Mar 14 2019 7:26am
by Electric Earth
Just wanted to throw in my opinion for not running high psi in a fat bike tire. Generally the bigger the tire, the lower psi you run. You don't run more than 30psi in a car, and that weighs a literal ton for the tiniest of cars. Motorcycles also don't run high psi. As long as the tires are staying planted and tracking well in the corners, I wouldn't feel any need to go higher on psi. It'll just make your ride worse, and make you more apt to bounce around if you hit a pothole or something. I don't wanna be bouncing around at 40mph personally...

What kind of tires and what kind of bike do you have?

Re: Fat tire speeds

Posted: Mar 14 2019 9:39am
by kcuf
250 lb rider

front fat tire 10-12 psi

rear fat tire 12-15 psi

soft comfy ride quality

no complaint or problems

Re: Fat tire speeds

Posted: Mar 14 2019 2:27pm
by LeftieBiker
You don't run more than 30psi in a car, and that weighs a literal ton for the tiniest of cars.
NOT true! While a car tire CAN run at 30psi, that's too low. The lowest car manufacturer suggested pressure - and it's too low - is 32psi, while more typically it is 36psi. Those wanting good economy and handling, as opposed to just a soft ride, run their tires at 38-44psi, and some go even higher. Do you even have a car...?

Re: Fat tire speeds

Posted: Mar 14 2019 3:41pm
by fechter
I'm not aware of a speed rating for fat tires.

I've had mine up to about 35mph going downhill and I keep thinking that if a tire blew out, I would probably be seriously injured. With smaller tires, one can blow out and you have some chance of controlling the bike enough to pull over. With a fat tire, I'm not so sure. I've never had one go flat (yet).
Img_0711A.jpg
Img_0711A.jpg (129.77 KiB) Viewed 622 times

Re: Fat tire speeds

Posted: Mar 14 2019 8:19pm
by epower-1
thanks for all the info
let me clarify
the bike is a EEB endure and my trike is a KMX
the tire is the new for 2019 4 inch wide fat tire slick
on 20 inch rims at 20 psi
here are some shots
both the bike and the trike will hit 40 mph on the straights
EEB SM.jpg
EEB SM.jpg (421.89 KiB) Viewed 604 times
yin yang.jpg
the frames are strong and I run good rims
what say you

Re: Fat tire speeds

Posted: Mar 15 2019 12:07am
by Chalo
LeftieBiker wrote:
Mar 14 2019 2:27pm
You don't run more than 30psi in a car, and that weighs a literal ton for the tiniest of cars.
NOT true! While a car tire CAN run at 30psi, that's too low. The lowest car manufacturer suggested pressure - and it's too low - is 32psi, while more typically it is 36psi. Those wanting good economy and handling, as opposed to just a soft ride, run their tires at 38-44psi, and some go even higher. Do you even have a car...?
Back when I used to drive cars, I came across some that had manufacturer recommended tire pressures as low as 28psi (posted on decals on the car's body). You are free to believe you understand these things better than the engineers who determine them through exhaustive testing, but you'd probably be the only one who believes that.

It's probably best to start from what the manufacturer recommends and make small incremental changes if you think you have different objectives for the vehicle than they do. Keep in mind that the thing is a system, and changing something basic like tire pressure affects not only rolling resistance, but tread wear, shock absorption, suspension characteristics, traction, noise abatement, and mechanical wear of other components.

I used to raise the pressure to near the tires' rating before setting off on a long highway road trip, where I could count on good surfaces, straight line routes and predictable conditions. Then when I got off the highway, I would lower the tire pressure again to the recommendation for the car.

Re: Fat tire speeds

Posted: Mar 15 2019 8:50am
by fechter
Usually the thing that limits the speed rating of a tire is heat buildup. You can test your tires by running fast for a while, then stop and feel the tire temp. Tires get a lot of air cooling, so if they feel warm, you know a lot of energy is being dissipated.
I don't think you will have a problem at 40mph with those.

Re: Fat tire speeds

Posted: Mar 15 2019 9:51am
by kcuf
i say worrying about nothing

enjoy your nicely built ride

Re: Fat tire speeds

Posted: Mar 15 2019 11:46am
by thradad
fechter wrote:
Mar 14 2019 3:41pm
I'm not aware of a speed rating for fat tires.

I've had mine up to about 35mph going downhill and I keep thinking that if a tire blew out, I would probably be seriously injured. With smaller tires, one can blow out and you have some chance of controlling the bike enough to pull over. With a fat tire, I'm not so sure. I've never had one go flat (yet).

Img_0711A.jpg
fechter,

Do my eyes deceive me, or is that a gel saddle with coil suspension on a suspension seatpost on a full suspension bike on fat tires? :shock: Looks comfy as heck, but you might ride over a Volkswagen without noticing. :lol:

Re: Fat tire speeds

Posted: Mar 15 2019 1:18pm
by fechter
thradad wrote:
Mar 15 2019 11:46am
fechter,

Do my eyes deceive me, or is that a gel saddle with coil suspension on a suspension seatpost on a full suspension bike on fat tires? :shock: Looks comfy as heck, but you might ride over a Volkswagen without noticing. :lol:
OT here, the saddle has elastomer springs, but otherwise correct. It is comfy as heck, but haven't noticed any road-killed VWs in my path yet. I'd say the Thudbuster made the biggest improvement.

Re: Fat tire speeds

Posted: Mar 15 2019 1:55pm
by LeftieBiker
Back when I used to drive cars, I came across some that had manufacturer recommended tire pressures as low as 28psi (posted on decals on the car's body). You are free to believe you understand these things better than the engineers who determine them through exhaustive testing, but you'd probably be the only one who believes that.
Those low recommendations for tire pressure are to provide a soft ride that makes the car seem luxurious, and most competent engineers would not be happy with them. The scenario you are picturing, with guys in white coats and "exhaustive testing" is a PR fantasy. Your position is one I usually get from women who know nothing about cars or tires - I'm surprised to read it here. Anyway, the best thing to do is look at the maximum rated pressure on the tire (not on some label on the car often put there many years ago, for different tires, when the car was new) and then inflate them to no less then 20% below that. I do 10% below, and have for 20+ years.

Re: Fat tire speeds

Posted: Mar 15 2019 4:52pm
by epower-1
dudes thank you for all the feedback
everyone was very helpful
I have been working on this bike for about two years now and it has gone through many changes
and I think that I am going to like this new tire rim set up the best
I don't ride off road cause I am a geezer now I did my fair share of that when I was younger
this bike is for the street and bike paths
I also found out today that the max pressure is 30 psi so that makes me feel better about the handling
I chose this set up for the 20 inch rims and with the fat tire the OD with the tire mounted is 22.9 inches that puts the gear ratio right where I want it for the small edge motor running 96 amps and 72v
when I get the front rim in I will post some shots with it all together
Thanks so much again for sharing your opinions
Peace Bill.

Re: Fat tire speeds

Posted: Mar 15 2019 6:31pm
by LeftieBiker
Hey, even a Geezer can try a packed trail once in a while. I intend to so so! :wink:

Re: Fat tire speeds

Posted: Mar 16 2019 7:29am
by dogman dan
Re speed ratings for tires. I do know from experience, if you run 40 mph on a tire that is getting low, like maybe below 20 psi, it heats the tire a LOT. Mine melted from the inside, looked fine outside, but when I took the tire off it had melted on the inside, looking like a bowl of spaghetti got in there. Cord all over. That took about 20 min of run time, but it was during a race, so you might get longer if you are not cornering so much.

You should have no problems with 30 psi, but my experience has been that there is a huge handling difference between 30 mph cruise, and 40 mph. That's frame related more than tires.


Anyway, if you inflate to the psi they intended for fat tires, don't run 40 mph for long. If you want to run fast on a fat tire, get motorcycle or moped rims and tires, that are wide, durable, and intended for fast speeds. Many have done that here. That is how you do a fast, street, electric bike best.

Re: Fat tire speeds

Posted: Mar 16 2019 1:04pm
by 999zip999
It depends on the tire rim combo. The first 4in pedago fat bike had a hard time keeping the tire on the rim. The tire with the spider design was really bad. But pedago use the cheapest of cheap parts as the rule.

Re: Fat tire speeds

Posted: Mar 16 2019 1:50pm
by epower-1
these are bicycle parts the rim is a 3 inch wide double wall fat tire rim clincher with 12 gauge spokes
and the tire is the new for2019 veetire 20x4 slick
I wanted to stay with bike parts for the weight
I know every one does the moto rim with either a moped tire or a shinko motorcycle tire 241 or 244
I wanted to do something other than the norm that's why I went with this set up lighter and wider than
the moped or motorcycle tire
still waiting for the front rim from Europe though man like 3 weeks now
I guess 3 day shipping is out the window

Re: Fat tire speeds

Posted: Mar 16 2019 5:02pm
by epower-1
well still no rim but while I'm waiting I must say fechter that's a bad ass bike post up some more shots
so we can check it out
while we talk fat tire speeds

Re: Fat tire speeds

Posted: Mar 16 2019 5:40pm
by John in CR
I'd run the 30psi the tire is rated for. Those are more like the 3" Kenda Flame 20's that I used to run instead of the fatbike tires meant for sand and off road, and my Kendas were rated for 40lbs. FWIW, I did 2 runs of over 100mph with the ultra-cheap Kendas and they're still on a friend's ebike with well over 10k km on them by now, though they're getting a bit bald. I use moto tires now for better piece of mind and less frequent air fills.