| Author | Message | ||
     Berkshire |
I did a search and found a handful of references to wider wheels - whether by replacement or widening - scattered among discussions of other topics, but no posts from anyone who has actually done it or even any detailed plans of how it might be done or what other bikes have wheels that might fit. I'm mainly interested in widening the stock rear wheel, or finding a 16" wheel about 4" wide from another bike that can be made to work. Here's why:  [edit: these profiles are exaggerated - an accurate graphic is shown in the post below.] The graphic shows (roughly!) the tread profile from a 140/70-16 tire. The curved arcs at top represent the part of the tire that has the tread on it, in cross-section. The one on the left is 5.60" wide (142mm) and spans 90 deg. of arc. This represents what you'd get if the tire was mounted on a 4" wide wheel. The one on the right is 4.88" wide (124mm) and spans 180 deg. of arc. This represents what you get mounting the tire on a 2.75" wide OEM Blast rear wheel. The measurements came from a Michelin Gold Series tire (see thread in this forum), but the basic shapes would apply to any tire mounted on a wide rim vs. a narrow one. It looks to me like the wider wheel would give a wider, flatter contact patch, and the tire would certainly be more stable on the wheel. Another benefit is that the tire would wear more evenly, instead of just wearing a bald patch down the middle while the sides remain practically brand new. The easy answer is custom wheel widening, but the info I've seen online indicates a $500 cost by the time you add shipping, and that's not even including the cost of a "donor" wheel. (Message edited by berkshire on April 23, 2008) | ||
| Berkshire |
oops! I think I should have put this in the "Wheels & Tires & Brakes" section - EZ, can you move it? | ||
| Gearheaderiko |
That is all correct! Thats why its difficult to find a wider tire that will still profile wide on the Blast rim. $500 is about right and they can convert to 17" too! The downside is that, besides cost, the Blast wheel is already on the heavy side, so you'd be making it heavier. I doubt though that it would weigh as much as a Big Twin/Sportster rim. Its only money! www.kosman.net | ||
| Reuel |
What's it cost to have a wheel cut out of a blank chunk of aluminum? I've seen it done on Discovery channel. | ||
| Ezblast |
I'd like to point out that the 140/70 tire is in fact only 10 over on its size ratio on a stock Blast rim and there is very little deformation on the Avon Viperstrykes, and that they handle very well indeed while giving over 1500 miles more than my old favorites the now stock Pirrelli. EZ | ||
| Gearheaderiko |
I'd also like to point out that all 140/70's are not created equal. Just like all stock sized tires vary in actual size. Cut out of a chunk of aluminium in a custom size? WoW! I doubt its cheap! | ||
| Berkshire |
"..the 140/70 tire is in fact only 10 over on its size ratio on a stock Blast rim..." How do you figure? As I understand it, the "wider section width + lower profile" tradeoff only applies to keeping the overall height the same (or close), which is useful for things like speedometer accuracy and not rubbing on the swingarm and shock mounting tab. Lower profile doesn't compensate for insufficient wheel width - if anything, I'd expect lower profile tires to suffer worse deformation than taller profile tires when mounted on too-narrow rims. | ||
| Berkshire |
After realizing a flaw in my technique, I took another measurement and revised the profile drawing - this should be pretty accurate:  [edit: that's a Mich GS 140/70 on a 16x4 rim on the left; same tire on a Blast rear wheel on the right.] (Message edited by berkshire on April 24, 2008) | ||
| Berkshire |
Reuel, billet wheels for harleys are rather expensive, and that's for an "off-the-shelf" product - a custom set would probably cost much more. ...but if you know a generous person with a computer-controlled 5-axis mill, I'd be willing to CAD up a model! | ||
| Berkshire |
Erik, thanks for the link. That's the best web info I've seen, and the price includes purpose-made flanges so you don't have to buy & ship a donor wheel. Hopefully the flanges aren't just made in 17" diameter! One idea I had was to get all of the extra width added on the brake side of the wheel instead of half on each side. Changing the spacers would re-center the tire and correct the caliper location. A different pulley would be used, and with the drive side of the wheel offset toward the swingarm, less spacer would be needed between pulley & spokes. Of course the "big idea" behind that was to save 1/2 the money by only having one side of the wheel modified, but the price sheet shows it costing $75 MORE for asymmetrical widening - but maybe that's assuming both sides are to be modified, just not the same on each side. When I can half-afford it, I'll call and ask! Anybody notice the "rounded" rim flanges? bitchin'!!! | ||
| Berkshire |
Here's what they'd look like with 3/16" rubber worn off flat down the middle: (140/70 on a 4" rim LEFT; 140/70 on a 2.75" rim RIGHT)  I notice that XB's get the same flat wear down the middle, but it's not nearly as bad as it was on my 120/80 Pirelli, because the XB tire is so much wider and the profile is much flatter, so the transition isn't as sharp. The 140 on a wider rim looks like it'd be somewhere in between. | ||
| Reuel |
When my wife asks what I want for my birthday, I'll tell her I want a computer controlled 5 axis mill. She'll see the price and tell me what she really thinks! | ||
| Gearheaderiko |
Thank EZ for the link! You may find that 17" rims have only a slightly bigger diameter than the 16" with a 140/70. Also 17" sportbike tires can weigh less than Blast tires and there is a better 17" tire selection. Something to consider. | ||
| Berkshire |
Thanks, Ed! Yes Erik, I'd thought of those things, and also the BIG difference, radial construction! As far as I know, all the Blast & scooter tires are bias-ply, while the 17" sport bike tires are all radial. On the other hand, the Blast & scooter tires are WAY cheaper... A riding buddy with an XB9R was SO happy about finding a rear tire on clearance for $175, and I was thinking to myself "wow, I could get 3 Pirelli's shipped to my door for that price!" ...or two dual-compound tires. As expensive as wheel widening is, the combined total for a used set of XB wheels, forks, and front brakes would certainly cost much more. With unlimited funds, the XB hybrid would be my choice... but my funds are FAR from unlimited! (Message edited by berkshire on April 23, 2008) | ||
| Berkshire |
Does anyone have a fresh Pirelli in the OEM size they can measure for profile comparison? Here are the measurements I need:  Inflated Width - I measured at 33 psi with an outside caliper, adjusted to get very light drag over the edges, then measured caliper opening.  Tread face width - I rolled a straight edge across the face of the tread, starting at one edge and then marking where the other edge ended, then measured the straight edge to the mark. ...like this:  | ||
| Gearheaderiko |
124mm wide 179mm outside rim edge to center tread(diameter). 160mm full tread face. From race tire in good condition. 33 PSI | ||
| Ezblast |
Please note folks - each tire of different makers and type is a bit different in size profile and road abilities - Would not recommend the Kendas, yes to the Avons, will find about about the Pirelli my self a bit later - but I'm sure its good and stick already - its its life that has me curious, maybe later about others as I go along and other folk try different tires - lol EZ | ||
| Gearheaderiko |
Concur!Thats what I've been saying all along...but it bears repeating. Warning: Installation of improperly sized tires can cause injury or death! | ||
| Berkshire |
OK, this is what I get for the Pirelli 120/80   | ||
| Berkshire |
Above comes from Erik's 124 & 160 measures - not sure what is the 179, can you sketch? Measures from all other tire types wanted, the fresher the tire the better. Anybody got an XB in the garage? | ||
| Berkshire |
Crap - only 3 months have gone by and my "new" Pirellis are already down to the last ghost of a tread in the middle! ??? $60 for another new MT75 - vs. - $500 for wheel widening ??? Aaaarrrggghhh! I can't afford wheel widening - looks like it'll be another MT75... | ||
| Xgecko |
Avon's | ||
| Berkshire |
A more durable compound like the Avons will wear longer, but it won't stick as well. Even with the Pirellis my back end slips out a bit when I pull out of my neighborhood - and a "cold" tire here is 80+ degrees! If the Avons need more warmup, then that's not the way I want to go. There is a dual-compound Metzeler in the stock size, but it's hard to get, expensive, and it's a scooter tire rated for light loads and lower speeds. The problem is that all of the wear is concentrated on a narrow strip down the middle of the tire. This is caused by the Blast's rear wheel being very skinny in relation to the tire width. Most sport bikes use a rim that is less than an inch narrower than the tire section width, but the Blast rim is TWO inches narrower. This pulls the sidewalls in and makes the tread surface of the tire very round, so not very much of it is touching the ground, meaning all the wear is concentrated on a small area. It also means that all of the GRIP is concentrated in a small area. I talked to Kosman today - the cost for widening up to 1-1/2" is $425, plus shipping. This applies to equal widening on both sides, OR to all of it on one side and the other side untouched, which might be useful if planning to change the pulley, as there aren't any other belt bikes with a pulley that's 2" wider than the belt - I didn't ask about getting a slight amount on one side and the bulk of it on the other, but that may be $75 extra. Also, it could take FIVE WEEKS, so the plan would be to find another wheel and have it shipped straight to them. Considering the expected longer tire life, the widening should eventually pay for itself, and the better grip would be pure frosting! Or plan B, an XB or tuber wheel. But without detail drawings of their axle dimensions (or a pile of parts to play with!) there's no way to know what would fit and/or what modifications would be needed to make it fit. Besides that, if I swapped the rear, i'd want the front to go with it - and since the Blast already has a semi-ZTL front rotor and I don't want retro-tech, it would have to be XB, not tuber. Then I'd need the forks, and front brake, and... Anyway, a Pirelli is on its way - I need fresh rubber NOW, not in 5 weeks, and cash is too tight for either plan right now anyway, but one of these days... | ||
| Reuel |
What pressure are you running on that MT-75? You might try dropping it a couple PSI to get a bigger contact patch. I've never had a Pirelli slip. | ||
| Ezblast |
I agree - or the Avon 63, also, perhaps a better shock may help, remember, formula riders rode on tires this size in the past, when suspensions where not good - lol EZ | ||
| Xgecko |
the 51/52 avons are not a good choice for colder weather I had mine break loose on me a bunch and it was downright scary at times, in general they take way way too long to heat up is you live in colder climes. the 63's whether in stock size or the big brothers are much better at heating up and they last longer to boot. I commuted all last winter except when the temps stayed below 20degrees and I never had traction problems from a 63 | ||
| Berkshire |
I'm running it at 34 cold - 5th gear gets a little sluggish if I drop it to 30, and it seems to wear faster. It does stick a little better, but not enough to justify the hit on top end and longevity. The worst slippage is pulling out of my neighborhood - I'm pulling out between traffic from a stop, so it's a WOT dash diagonally across an asphalt road, with a hard lean when I get to my lane, which is when it slips. It doesn't slip in higher gears, just when leaned over and WOT in first. Maybe also a tiny bit in 2nd, but only enough to get out of shape when in 1st. Right now it's 80 degrees in the middle of the night here, and high 90's in the afternoon. In the winter it gets down below 40 sometimes, but I don't do much riding then - with the humidity here 40 feels like 14! I don't think it would be accurate to say I've had traction *problems* - I just don't want to switch to a tire that's less sticky than what I have now, and it bugs me that I'm replacing tires so frequently when they still have almost full tread depth over 2/3 of the surface! I think all of the available tires would have *better* traction AND longevity if mounted on a wider rim - it would be like having the contact patch you'd get at 15 or 20 psi, but without the tread distortion, and with the speed & stability of runnning at regular pressure - plus slower wear because you're spreading it over a wider patch and getting "off" the middle part of the tire more. Regarding the shock, YES, that little bugger could be doing more! There is noticeable "side-step" when bumps are encountered on moderate to hard turns, and a guy riding behind me said he could see the back tire coming off the road on some bumps while riding straight. | ||
| Rusty7983 |
i need a new rear tire. what would be a better choice( i want to have a long lasting tire)? metzeler sportec 130/70/16, pirelli mt75 120/80/16(it a soft tire right?) or spend 20 more for a pirelli diablo 130/80/16 or 30 more for a diablo 140/70/16. thanks | ||
| Gearheaderiko |
Is the "metzeler sportec 130/70/16" a rear tire? Usually that size only comes in a front. I only find a $6 price difference between the MT75 and 140/70 Scooter Diablo. $69-$75. I'd get the 140/70 or the Pirelli ST66 140/70 if the mileage reports for those tires are true. I have doubts that the 130/80 will fit with enough clearance. (130/80's are hit and miss on clearance) (Message edited by gearheaderiko on November 04, 2010) | ||
| Ezblast |
Concur! |
