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Discussion Starter #1
Sometimes ya just get it wrong. This is one of those times.



I mounted this tire on one of my spare rims, then dismissed it as being too stiff, too square, too heavy, too much hassle and expense, and maybe even dangerous. I set it aside because it wouldn't seat properly. The need arose for me to dismount the Bighorn2 I've been running, so I decided to take another shot at getting it on the rim so I could run it while I repaint my black rims.



It's a Maxxis Bighorn MT762, 27 x 8.50 x 14. Not to be confused with the ATV Bighorns, these are D.O.T-legal light truck tires. Loaded radius is right at 13" (26 1/4" total height @ street pressures), weighs 27 pounds, outline white letters one side, black on the other.











Tread view:







Rode the crud out of it today. The only handling issues I uncovered were the exact opposite expected. I thought it would cause the front to tuck under in the corners, but while it did this to some extent I didn't find it unsafe. The square face of the tire was felt more when coming OUT of a corner, as the bike tended to straighten up a little prematurely. Again, doable. No change in braking except in areas where rain runoff deposits dry sand on the asphalt here. Downright squirrelly in that situation, but I'm used to a stickier Bighorn2 and this is more like braking with the stock knobby.



Less slippsage in axle-deep sand than the ATV tire and more stable direction changes, which makes no sense at all, but it's true. Thoughts?



A little premature (haven't really wrung it's neck over rocks, or in the mud) but I was at least pleasantly surprised to find that it wasn't particularly scary on the road and danged impressive in sand.



Upsides:



TONS of bulletproof tread. Probably outlive us all.



Allows greater range of chain adjustment than my Bighorn2 without interference issues in a stock-length swingarm.



D.O.T.-legal. No more sweating bullets and dreading t-stops.



Relatively short at 26". Far less felt power loss despite its weight, probably due to harder compound.



Downsides:



Requires removal of inner chainguard bracket.



DANGEROUSLY high seating pressures. 120 PSI for this one.



$150+ retail. Not exactly a cheap experiment if it explodes during seating or doesn't prove to meet your needs or terrain.



There aren't very many options left in 14 inch road-legal tires these days, but they might be worth playing with, after all.
 

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Thanks LB, nice report and good info. I don't know that I would have expected it to behave that well with those square shoulders and as stiff as it looks, nice surprise.

I don't envision going to something like this tire, but I know I'm sure not impressed with the stocker. (back or front) They seem ok in our rocks, but were helpless in the heavy mud...... so bad it was hilarious!



Thanks again for the report, I look forward to further input as you accumulate miles!



Bag
 

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Is it radial or bias?
 

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Discussion Starter #4

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There is actually a whole MC subculture that swears by car tires on their bikes...they have a far superior straight line contact patch and a near equal CP in the turns...now if you race or are a canyon carver that loves to crank it on the edge, then that may be a different story. For normal street cruising it should be fine, save for they are way overbuilt for a bike and add needless weight.



http://www.motorcyclecruiser.com/tech/0907_crup_mounting_car_tires_on_motorcycles/index.html



http://www.youtube.com/watch?v=xaIj1XrmvLM
 

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It just doesn't look like it has enough "bite" for me... we need to schedule an a/b comparison ride - this tire versus my Duro.
 

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Discussion Starter #7
It just doesn't look like it has enough "bite" for me... we need to schedule an a/b comparison ride - this tire versus my Duro.




Yer on!



I have no idea how this tire works yet. We'll call it "research".



Yeah, dat's it.



Seriously, even though I've done it on other bikes I don't neccessarily advocate "Darksiding" bikes as a general practice. It's on a "per bike" basis and generally works better on heavier road bikes.



First, you need a tire which is tough enough to survive the mounting process itself. In some cases mounting alone can weaken, separate or rupture the tire carcass. Then it has to flex well enough to keep most of its tread on the ground, which involves a lot of exerimentation with tire pressures and a willingness to start all over again with some other tire if yours doesn't work out.



That said, I think maybe our bikes are light enough and slow enough to warrant experimenting, maybe because some of the negatives of car tires may be more livable or their effects less abrupt, or maybe I'm just trying to convince myself of it.




Anyway, if yer gunna mess with this, know the risks. I'm pretty conservative when it comes to things like this, so these are just my opinions.



I don't believe in bead trimming personally, so for me this means that a tire has to seat on its own. I generally don't want to ride on anything which has already been subjected to 100+ pounds of bead seating pressure. The two lighter car tires I tried to stuff on TW rims started making cute little tearing sounds around 90 PSI. The Bighorn or something similarly constructed would be safer to mount if seating pressures were high.



Anyone who's ever witnessed a sidewall explosion can tell you that it's entirely possible to get yourself killed mounting a tire. A tire rupture at 100+ PSI can launch a tire 30 feet into the air and take your head off in the process.



Tire shops have cages to contain the explosions. My poorboy method is to roll the tire up in a 10 foot section of chainlink, stake the chainlink to the ground with metal stakes, then get as far away from it as possible while inflating.



This Bighorn sat for a week @ 110 PSI. I then pushed it to 120. Two days later it woke me up at 3 a.m. when it finally seated. Sounded like shotgun blast. A lighter tire might not be worth riding on after being subjected to such treatment. Be careful with this.



 

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10 ply "C" rated radial.











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"C" Load range would be a 6-ply rating. Usually, modern tires have a higher "X-ply rating" than the actual number of plies because modern materials are stronger than the old nylon. Having 10 plies and a 6-ply rating would be very unusual. 10-ply tires often have a G Load Range, or 14-ply rating. Is it possible you've mis-read something on the sidewall? If it really is a 10-ply tire I'd think inflating it would be optional, Maybe just drill holes in the rim and screw the tire to it, then cut a few holes in the sidewall to let the water out? We used to do airplane tires that way on swamp buggies.
 

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Discussion Starter #9
"C" Load range would be a 6-ply rating. Usually, modern tires have a higher "X-ply rating" than the actual number of plies because modern materials are stronger than the old nylon. Having 10 plies and a 6-ply rating would be very unusual. 10-ply tires often have a G Load Range, or 14-ply rating. Is it possible you've mis-read something on the sidewall? If it really is a 10-ply tire I'd think inflating it would be optional, Maybe just drill holes in the rim and screw the tire to it, then cut a few holes in the sidewall to let the water out? We used to do airplane tires that way on swamp buggies.


I misspoke. 4 ply, 6 ply rated. But it's an oddball in that it's equivalent to 10 ply rating for puncture resistence due to the steel content. Legendary for deflecting large sharp objects. I'm not sure how well it will conform to rocks and such for that reason. With so few 14" choices to begin with this was physically the smallest I found locally at the time. I chose it due to my personal superstitions regarding carcass stretching. Seemed well-founded after the two previous failures.



I suspect a less gnartly-looking tire may work as well or better provided it didn't self-destruct during mounting. Brand-to-brand bead and sidewall construction differences might even allow some other lighter tire to pop on at 60 PSI.



I'm not presenting this tire as a definitive answer. Its self-righting tendency seems insignificant now, but it might get old after a few hundred miles. Who knows.

But if a few of us can spare the coin and the time there may be some good successes to be had in the car tire world for certain purposes.



I don't recall who among us was first to try an ATV tire, but I remember being pretty sceptical until mine hit the road. I guess I'll see if upping the threshold is worth the effort or not.
 

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Other tires to consider:

BF Goodrich All-Terrain T/A KO LT195/75R14/D

Super Swamper Radial TSL Tires LT225/85R14

Super Swamper TSL Bias Tires 28x8.50-14LT

Super Swamper SSR Tires 27x9.50R14LT

General Grabber AT2 27X8.50R14LT

Firestone Winterforce 195/75R14

Mastercraft Courser Radial LT 195/75-14



Studded mudgrips would rattle some cages.
 

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Discussion Starter #11
Already did the homework on most of the above. All but a couple are either too wide, too tall, or both.



The problem is that they don't arc. Anything much over 26" tall will hit the curve in the crotch of a stock swingarm. In contrast even my 27.5"+ tall ATV tire will go all the way forward in the swingarm without hitting the tread edges.



Anything wider in total section than about 8.25" mounted width will hit the chain. Our narrower rims will pull this in slightly, but not much. Figure sidewall-to-sidewall width will only pull in about 1/4"- 1/2" narrower than manufacturer spec for a proper 7" car rim. The tire I chose clears in both dimensions.



Like I said, not a lot of choices.



On the plus side. today I found a super-slippery tire lube in the form of "Ice" brand liquid synthetic car polish. Worked like a champ.
 

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Relative to the BigWheel, you guys seem to have a lot of choices. The BigWheel came with a 23" tire on a 9' rim. Nobody make those at all and the selection of 9" atv tires is dismal.



There seems to be a lot more innovators with the TW than in the BW world. Keep up the good work.



Regards,



Mr. BigWheel
 

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Discussion Starter #14
OK, kids. Look and learn, as I re-re-eat my own words:















Nuff said?



That's right. The taco'd sections of the rim weren't taco'd by rocks. This is (was?) a new rim. The tire forced itself off the rim by pneumatic pressure at only 85 PSI.



Five things happened simultaneously here, and I have no further interest in knowing which was the chicken or which was the egg. 1. The sidewall blew. 2. The rim bent outward in two places. 3. The tube blew. 4. The tire bead snapped. 5. I have been rendered stone deaf for now.



Any questions?



Leave car tires alone, and seriously reconsider remounting an ATV tire after once stressing it for bead seating. Seriously rips them apart internally and clearly our rims aren't up to it, either.



Which was my original premise. "Definition of insanity" stuff on my part. My bad.
 

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WOW! I hope you are ok. When did it happen? Was it cold/hot out, in a corner, etc.
 

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OK, kids. Look and learn, as I re-re-eat my own words:















Nuff said?



That's right. The taco'd sections of the rim weren't taco'd by rocks. This is (was?) a new rim. The tire forced itself off the rim by pneumatic pressure at only 85 PSI.



Five things happened simultaneously here, and I have no further interest in knowing which was the chicken or which was the egg. 1. The sidewall blew. 2. The rim bent outward in two places. 3. The tube blew. 4. The tire bead snapped. 5. I have been rendered stone deaf for now.



Any questions?



Leave car tires alone, and seriously reconsider remounting an ATV tire after once stressing it for bead seating. Seriously rips them apart internally and clearly our rims aren't up to it, either.



Which was my original premise. "Definition of insanity" stuff on my part. My bad.


So this happened during mounting? I wonder if your boycott on bead trimming had a contribution to the undesirable result?
 

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Glad you're ok Russ. Still working on my new front end; glacial pace. Old pads are in, but having trouble building pressure in hose. Pumping lots of fluid though.


Still want to put together a Mojave Road trip this spring.
 

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Discussion Starter #19
So this happened during mounting? I wonder if your boycott on bead trimming had a contribution to the undesirable result?


Like I said, this ain't my first rodeo. I can tell you from related past experience that the effects of bead trimming will rear its ugly head at a far less opportune time than when mounting. The tire will fly off the rim when the bike is underway and the bead finally lets go because it is no longer bound in its original rubber matrix. Been there, done that.



The message here is that this tire was destroyed internally by the initial seating pressure. The proof of that is that it subsequently self-destructed at a much lower pressure when I tried to remount it.



Unless you have x-ray vision there's no way to tell to what extent this has happened. You may get it mounted, lower the pressure to normal and motor off for thousands of trouble-free miles. Then again, it may blow yer head off at 50 PSI.



An inexact science at best, and I'm not here to lord over anyone as some sort of expert on the subject, but the pictures speak for the worst case scenario.



You pays yer munny, and makes yer choices.



Third time's a charm for slow learners like me. You'll have to do your own math to decide how many rims and $150 tires you're potentially willing to invest in. But if you manage to find a tire that pops on at 60 PSI i'll be the first in line to steal yer homework, cuz so far mine ain't worth stealing.
 
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