EBike Tire Speed Rating

[speedyebikenoob]

The stock tires on the bike are Bontrager XR2s, yeah the rear one wore really fast, but I guess that's to be expected when dumping 2400 watts on the rear wheel?

Not really, unless you're lifting it with your feet so you can spin it to burn rubber, or you skid it on the pavement a lot.

No idea what the TPI of those tires are though, but I ran them at around 40-45 psi. The front still seems fine though. I admit I was somewhat careless with these tires, I didn't check the tire pressure as much as I normally would but I don't think it ever dropped below 35.

What pressure range do they list on the side of the tire?

Too low pressure can allow sidewalls to flex so much that they begin to peel and crack (a problem I've had with Kendas regardless of tire pressure), and then the fabric begins to tear, and the tube can herniate out the side and catch on rim brakes or frame and be torn open.

But if that wasn't the failure mode, then pressure isn't likely the issue.

The rear tire is worn to the point where the "nubby" things in the center of the tire are non existent and completely flat. I think it also might have wore out so quickly because I originally had the battery at the back of the bike for the first hundred miles,

That shouldn't matter--it shoudl actually *help* because it keeps the wheel on the ground, helping to prevent spin, which like skidding during braking causes excessive wear.

If the surfaces it's used on are very rough, sharp edged, they'll wear faster, or if there's sand on a hard surface, or stuff like the flinty dust we get around here that acts like sandpaper dust on the roads (worse on concrete paths), they'll also wear faster.


The softer the compound, the grippier the tire...but the quicker they wear out.

Given the choice, I prefer grippier, even if I have to replace them more often, because if I have to make a sudden avoidance maneuver due to other traffic, I need to know the tires will stick if I want them to. However..I also want to be *able* to break them loose to slew the trike out of the way quicker than I could by just steering, so the tires I'm using are moped Shinko SR714s (IIRC--sometimes I misrememeber the number, but you can find them in my SB Cruiser thread), which are fairly sticky, but will still let me "drift" the rear end if I manipulate brake and power and shift my weight correctly, so if I have to I can change lanes in a few feet at most, instead of a few trike lengths (or I can make a corner without tipping the trike by drifting partly around it, if someone is tailgating me at a speed higher than I can normally turn at).

(I use the moped tires because of their thickness and multi-ply construction, which along with thick moped tubes help keep me from having to deal with flats).

Anyway....the wear doesn't have anything to do with "speed ratings" of the tires.

It says the max is 50 PSI. I thought MTB tires wear faster on pavement than they would offroad? Whoa you can drift your trike? By hitting the throttle or through the rear brakes? I feel like I can get the rear end to slide out on my bike if I hit the throttle hard enough but I'm not gutsy enough to do that, atleast not yet. Plus I have too many speeding tickets (two within a month ) and I would hate to get another point on my record by "riding in a reckless manner" or whatever they would get you for, I'm not even sure how it works on bicycles. :lol:

 

[amberwolf]

It says the max is 50 PSI.

What's the minimum? That's the important number, if you're worried about too little inflation.

I thought MTB tires wear faster on pavement than they would offroad?

Probably, because the knobbies don't provide a continuous surface, so there's less surface to take what wear does happen, than a road tire.

Whoa you can drift your trike? By hitting the throttle or through the rear brakes?

My rear brakes are only the motors' braking function, no mechanical brakes yet. (other than parking brakes off an old wheelchair). So they don't "lockup", but if I touch them and shift my weight at the same time, then on most asphalt I can start a sideways drift for just an instant, enough to move where I want. Adding motor power can take me out of it. (in wet conditions it's easier, and either power or brakes can do it, as long as it's a sudden change).

It's not always perfect control...but being a trike I won't crash on my side from it. (on a bike you could easily tilt too far and slide it out from under you).

I feel like I can get the rear end to slide out on my bike if I hit the throttle hard enough but I'm not gutsy enough to do that, atleast not yet. Plus I have too many speeding tickets (two within a month ) and I would hate to get another point on my record by "riding in a reckless manner" or whatever they would get you for, I'm not even sure how it works on bicycles. :lol:

Dunno; you'd have to check your local laws about that.

But I recommend practicing all manner of maneuvers, on private land where you have permission to do it. You'll be able to be a safer rider for it; you'll learn the limits of your bike and yourself. Just get yourself good crash gear and helmet first.

 

[DRMousseau]

The stock tires on the bike are Bontrager XR2s, yeah the rear one wore really fast, but I guess that's to be expected when dumping 2400 watts on the rear wheel? Idk you tell me, you seem to have an equally or more powerful bike than I do. No idea what the TPI of those tires are though, but I ran them at around 40-45 psi. The front still seems fine though. I admit I was somewhat careless with these tires, I didn't check the tire pressure as much as I normally would but I don't think it ever dropped below 35. It was mostly road use with maybe twenty miles or so of offroading. The rear tire is worn to the point where the "nubby" things in the center of the tire are non existent and completely flat. I think it also might have wore out so quickly because I originally had the battery at the back of the bike for the first hundred miles, it's been moved to the center now. I'm also pretty heavy on the throttle, I like quick acceleration but it's not like I'm spinning the tire or anything usually, and as far as I can remember I've never actually locked up the rear tire for an extended period of time (>1 second). I'm guessing I maybe have 40 miles or so left on that tire before I have to replace it, I would hate to have a blowout. Frankly I don't really care about the stiffness of the ride, I'm totally fine with having my tires up to the maximum psi they can take if it means they'll last longer. A higher psi helps range anyways which is a plus.

Ahhh,... you noted SEVERAL specifics of my interest.

#1-REAR tire has major wear over front, NOT due to abrasive skids. Nothing really unusual, but demonstrates a typical distribution of your total weight from front to rear. All things equal,.... the rear will wear faster with greater weight load, and shows a need for increased rear inflation pressure over front. I believe Bontrager are a quality tire specific to Treks (?) but know little more of them specifically. Your combined weight isn't unusual, but if these tires are 2.35width or less, than they are likely rated at least 50psi,.... so your running a "little light", especially on the rear tire. Your 40-45psi would be better suited to tires 3" or more wide on a BASIC equipped bike. Again, your seem a bit "light" in pressure, relative to total weight of bike and all.

I personal have 2.35" "Big Apples" suggested 30-55psi and maintain them 55-60psi on the rear. With over 1200mi or more, I might expect as much yet remains. I DID neglect tire pressure to about 35psi for a couple weeks last year, and suffered that abraded, perforated tube failure along the sidewall line of my quality Schwalbb tube!!! DAMNIT!!!! But at high proper pressure, I've had a big 3" construction staple penetrate the tread, deflect from the carcass, out thru the sidewall skin, with little concern!!! Whew!!!

AND,... you noted MOSTLY road use!!!! These Bontrager's have a sparse open-lug tread designed for "hard-pack" w/loose surface. And I would guess a bit "softer" compound of greater grip. Pavement, especially concrete, can be pretty dang abrasive for these tread and compound styles, especially if inflation is just a bit low, and the sparkly spaced lugs squiggle a little. A bit surprised your front holds up so well!!! I would guess "aggressiveness" in riding style on pavement also contributes,... heck, gotta have some fun! I too enjoy some "heaviness",... especially pushin' hard on pavement around tight country curves of only 30mph speed limits.

All considered,.... I think your Kenda Kwick-9s at the higher psi rating will be a much better choice.

 

[DRMousseau]

It says the max is 50 PSI.

What's the minimum? That's the important number, if you're worried about too little inflation.

Dang! Jus noticed this!
Yes,... 50psi, about what I kinda expected. Remember too, that minimum is still relative to load!!! Your tires shouldn't typically "flex" much under load!!! Typically means other than heavy "fats" and such. In general, most flexing contributes to failures.

That "minimum" inflation where listed, is typically that necessary to maintain solid bead seat, and not fold from it.

 

[speedyebikenoob]

It says the max is 50 PSI.

What's the minimum? That's the important number, if you're worried about too little inflation.

I thought MTB tires wear faster on pavement than they would offroad?

Probably, because the knobbies don't provide a continuous surface, so there's less surface to take what wear does happen, than a road tire.

Whoa you can drift your trike? By hitting the throttle or through the rear brakes?

My rear brakes are only the motors' braking function, no mechanical brakes yet. (other than parking brakes off an old wheelchair). So they don't "lockup", but if I touch them and shift my weight at the same time, then on most asphalt I can start a sideways drift for just an instant, enough to move where I want. Adding motor power can take me out of it. (in wet conditions it's easier, and either power or brakes can do it, as long as it's a sudden change).

It's not always perfect control...but being a trike I won't crash on my side from it. (on a bike you could easily tilt too far and slide it out from under you).

I feel like I can get the rear end to slide out on my bike if I hit the throttle hard enough but I'm not gutsy enough to do that, atleast not yet. Plus I have too many speeding tickets (two within a month ) and I would hate to get another point on my record by "riding in a reckless manner" or whatever they would get you for, I'm not even sure how it works on bicycles. :lol:

Dunno; you'd have to check your local laws about that.

But I recommend practicing all manner of maneuvers, on private land where you have permission to do it. You'll be able to be a safer rider for it; you'll learn the limits of your bike and yourself. Just get yourself good crash gear and helmet first.

That's still pretty cool. The minimum is 30 psi so it seems like I was good. Yup I apply the same ideology to any vehicle I have, car or bicycle, it's good to know your limits and the vehicles limits. I think from now on I'll just keep them at the highest psi recommended, it seems like it helps with a lot, and you only sacrifice ride quality and maybe a bit of traction.

 

[speedyebikenoob]

The stock tires on the bike are Bontrager XR2s, yeah the rear one wore really fast, but I guess that's to be expected when dumping 2400 watts on the rear wheel? Idk you tell me, you seem to have an equally or more powerful bike than I do. No idea what the TPI of those tires are though, but I ran them at around 40-45 psi. The front still seems fine though. I admit I was somewhat careless with these tires, I didn't check the tire pressure as much as I normally would but I don't think it ever dropped below 35. It was mostly road use with maybe twenty miles or so of offroading. The rear tire is worn to the point where the "nubby" things in the center of the tire are non existent and completely flat. I think it also might have wore out so quickly because I originally had the battery at the back of the bike for the first hundred miles, it's been moved to the center now. I'm also pretty heavy on the throttle, I like quick acceleration but it's not like I'm spinning the tire or anything usually, and as far as I can remember I've never actually locked up the rear tire for an extended period of time (>1 second). I'm guessing I maybe have 40 miles or so left on that tire before I have to replace it, I would hate to have a blowout. Frankly I don't really care about the stiffness of the ride, I'm totally fine with having my tires up to the maximum psi they can take if it means they'll last longer. A higher psi helps range anyways which is a plus.

Ahhh,... you noted SEVERAL specifics of my interest.

#1-REAR tire has major wear over front, NOT due to abrasive skids. Nothing really unusual, but demonstrates a typical distribution of your total weight from front to rear. All things equal,.... the rear will wear faster with greater weight load, and shows a need for increased rear inflation pressure over front. I believe Bontrager are a quality tire specific to Treks (?) but know little more of them specifically. Your combined weight isn't unusual, but if these tires are 2.35width or less, than they are likely rated at least 50psi,.... so your running a "little light", especially on the rear tire. Your 40-45psi would be better suited to tires 3" or more wide on a BASIC equipped bike. Again, your seem a bit "light" in pressure, relative to total weight of bike and all.

I personal have 2.35" "Big Apples" suggested 30-55psi and maintain them 55-60psi on the rear. With over 1200mi or more, I might expect as much yet remains. I DID neglect tire pressure to about 35psi for a couple weeks last year, and suffered that abraded, perforated tube failure along the sidewall line of my quality Schwalbb tube!!! DAMNIT!!!! But at high proper pressure, I've had a big 3" construction staple penetrate the tread, deflect from the carcass, out thru the sidewall skin, with little concern!!! Whew!!!

AND,... you noted MOSTLY road use!!!! These Bontrager's have a sparse open-lug tread designed for "hard-pack" w/loose surface. And I would guess a bit "softer" compound of greater grip. Pavement, especially concrete, can be pretty dang abrasive for these tread and compound styles, especially if inflation is just a bit low, and the sparkly spaced lugs squiggle a little. A bit surprised your front holds up so well!!! I would guess "aggressiveness" in riding style on pavement also contributes,... heck, gotta have some fun! I too enjoy some "heaviness",... especially pushin' hard on pavement around tight country curves of only 30mph speed limits.

All considered,.... I think your Kenda Kwick-9s at the higher psi rating will be a much better choice.

Yup it was definitely rear heavy when I first started riding the bike. Now that I've moved the battery to the center I'm hoping it'll be better. Helps with stability too, it was just too wheelie prone before and the handling wasn't too great. Yea the tires are only 2 inches wide, and I really doubt I'll need the knobbies anyways considering I don't go on trails that often, so I can switch to something that'll last me longer on the road. We'll see, hopefully I can get atleast a thousand miles out of these tires. Whether or not that actually happens, idk, but I'm going to keep my fingers crossed haha.

 

[speedyebikenoob]

It says the max is 50 PSI.

What's the minimum? That's the important number, if you're worried about too little inflation.

Dang! Jus noticed this!
Yes,... 50psi, about what I kinda expected. Remember too, that minimum is still relative to load!!! Your tires shouldn't typically "flex" much under load!!! Typically means other than heavy "fats" and such. In general, most flexing contributes to failures.

That "minimum" inflation where listed, is typically that necessary to maintain solid bead seat, and not fold from it.

How much can I actually push over the rating though before it becomes a problem? I'd imagine it would be safe to go maybe 10-12 psi over what's recommended?

 

[DRMousseau]

It says the max is 50 PSI.

What's the minimum? That's the important number, if you're worried about too little inflation.

Dang! Jus noticed this!
Yes,... 50psi, about what I kinda expected. Remember too, that minimum is still relative to load!!! Your tires shouldn't typically "flex" much under load!!! Typically means other than heavy "fats" and such. In general, most flexing contributes to failures.

That "minimum" inflation where listed, is typically that necessary to maintain solid bead seat, and not fold from it.

How much can I actually push over the rating though before it becomes a problem? I'd imagine it would be safe to go maybe 10-12 psi over what's recommended?

There is really NO universally accepted and established testing standards in such regard as there is in say, an established ISO, SAE, DOT, etc. That "maximum" PSI rating is that which limits and minimizes tire deformation under max expected load conditions, as designed, established, and tested to mfgs "company standards". Therefore,... a reliable, long established mfg company, likes to maintain a higher standard than competitors.

What if your load is greater than typical??? What of tandems, that typically use the same tires?!? Well,...
..."How much can I actually push over the rating, of my hub motor, before it becomes a problem???"

As you can now see, there is no real definitive answer here, at best, only reasoned opinion. Your "safe" 10-12psi over, may exceed 100% of some ratings, and only 10% of others, and will also be depending on dozens and DOZENS of other factors.

While auto tires and motorcycle helmets are subject to various accepted and established standards of specific testing with mfg documentation,.... the bicycle/e-bike industry isn't, at least not to the same extent, YET!!!

 

[speedyebikenoob]

What's the minimum? That's the important number, if you're worried about too little inflation.

Dang! Jus noticed this!
Yes,... 50psi, about what I kinda expected. Remember too, that minimum is still relative to load!!! Your tires shouldn't typically "flex" much under load!!! Typically means other than heavy "fats" and such. In general, most flexing contributes to failures.

That "minimum" inflation where listed, is typically that necessary to maintain solid bead seat, and not fold from it.

How much can I actually push over the rating though before it becomes a problem? I'd imagine it would be safe to go maybe 10-12 psi over what's recommended?

There is really NO universally accepted and established testing standards in such regard as there is in say, an established ISO, SAE, DOT, etc. That "maximum" PSI rating is that which limits and minimizes tire deformation under max expected load conditions, as designed, established, and tested to mfgs "company standards". Therefore,... a reliable, long established mfg company, likes to maintain a higher standard than competitors.

What if your load is greater than typical??? What of tandems, that typically use the same tires?!? Well,...
..."How much can I actually push over the rating, of my hub motor, before it becomes a problem???"

As you can now see, there is no real definitive answer here, at best, only reasoned opinion. Your "safe" 10-12psi over, may exceed 100% of some ratings, and only 10% of others, and will also be depending on dozens and DOZENS of other factors.

While auto tires and motorcycle helmets are subject to various accepted and established standards of specific testing with mfg documentation,.... the bicycle/e-bike industry isn't, at least not to the same extent, YET!!!

I see, I'll just go with the highest amount I can put in there then.

 

[DRMousseau]

Personally,.... I use a general "rule of thumb", depending on tire size.

Up to 2" width,.... inflate pretty solid, tire should not deform or flatten any more than that barely noticed when bouncing very heavily on seat of stationary bike.

2'-3' width,... inflate very firm, tire shouldn't deform with full weight and load on stationary bike, and only noticeable when bouncing firmly on seat.

3"width and greater,.... inflate only enough that tire barely maintains profile with full weight load. Tire will be "soft and flexy" with any bounce or movement of load.

THIS, is pretty subjective, and the final tire pressure should be measured and compared with mfg rating and range. IF tire pressure is significantly outside rated range,.... then a different tire and/or size should be considered for needed load capacity within mfgs suggested inflation range.

My new build design will be VERY unique, with an overwhelming majority of total weight over rear tire, that will include TWO adults (rider & passenger carried in conventional motorcycle style) in addition to motor and controller (battery mid mount), and heavy tire. Since no bicycle or e-bike tire will safely carry such load within reasonable inflation rates, I will utilize a load-rated MC tire with a load capacity of 600+lbs. Tire width of about 6" will follow above "rule-of-thumb" with full load, and will be rather stiff in a rigid-frame with no passenger, but should still fall within mfgs sidewall ratings. Front tire on long forks will support the balance typical bicycle weight, and will be +3" width of e-bike quality. Max anticipated speed at any given time will always be less than 28-30mph.

 

[speedyebikenoob]

Personally,.... I use a general "rule of thumb", depending on tire size.

Up to 2" width,.... inflate pretty solid, tire should not deform or flatten any more than that barely noticed when bouncing very heavily on seat of stationary bike.

2'-3' width,... inflate very firm, tire shouldn't deform with full weight and load on stationary bike, and only noticeable when bouncing firmly on seat.

3"width and greater,.... inflate only enough that tire barely maintains profile with full weight load. Tire will be "soft and flexy" with any bounce or movement of load.

THIS, is pretty subjective, and the final tire pressure should be measured and compared with mfg rating and range. IF tire pressure is significantly outside rated range,.... then a different tire and/or size should be considered for needed load capacity within mfgs suggested inflation range.

My new build design will be VERY unique, with an overwhelming majority of total weight over rear tire, that will include TWO adults (rider & passenger carried in conventional motorcycle style) in addition to motor and controller (battery mid mount), and heavy tire. Since no bicycle or e-bike tire will safely carry such load within reasonable inflation rates, I will utilize a load-rated MC tire with a load capacity of 600+lbs. Tire width of about 6" will follow above "rule-of-thumb" with full load, and will be rather stiff in a rigid-frame with no passenger, but should still fall within mfgs sidewall ratings. Front tire on long forks will support the balance typical bicycle weight, and will be +3" width of e-bike quality. Max anticipated speed at any given time will always be less than 28-30mph.

Yeah, with two people you definitely want to beef up the frame and the tires. I won't have that issue though because luckily my bike is somewhat light and so am I.