motorcycle tire deformation
Safety Tips for Motorcycle Tires Let’s face it — at best, most of us have a passing understanding of our motorcycle tires. We spend only enough time on them to keep riding, but we want to keep riding on them all the time. Most of us have to kind of force ourselves to check the air pressure as often as we should — and even that will go out the window as soon as most bikes start coming with tire pressure sensors. That said, here are some quick points to know about motorcycle tires – tips that will keep you safer and riding longer. Though modern motorcycle tires are manufactured to very high performance and durability standards, taking them for granted is a mistake. And assuming they are all alike or basically the same as tires for your car, is not right. Motorcycle tires are unique and absolutely critical to your safety and long-term enjoyment of your motorcycle. Here are some of the key things to know about motorcycle tires. 1. Tires that appear to be the same can be very different in terms of how they are designed to be used safely.
Those dimensions and other information must be molded right into the sidewall of the tire.
part worn motorcycle tyres sussexUsing the same example above, 120/90B-19 60 H, here’s what the dimensions mean: 3. In addition to the speed rating, there is a code for the safe maximum load called the “load index.” In this example,“60” is the load index rating code, meaning the maximum load rating code means 551 pounds. Here’s a table of the DOT load index codes: 4. Each motorcycle is designed from the ground up with specific chassis specifications and suspension components that are intended to maximize handling, braking and stability with a specific type of tire in mind. Changing from bias ply to radial tires or vice-versa may adversely affect the handling of the bike, so don’t make that kind of change without consulting a professional on it. 5. Never mix bias ply and radial tires on the same bike — as with point 4, the bike’s handling could be adversely affected.
I’m not sure why anybody would ever do this, but I have heard of some folks doing it — never use automotive tires on a motorcycle, even if the size seems to fit. 6. Staying with the same type and size (even if by a different manufacturer) as was specified as original equipment (OE) for your bike is the easiest way to assure consistent performance. Going with wider tires to try to increase cornering performance, for example, may cause interference between the tire and suspension or driveline components. 7. Racing tires, while designed for high stress, high performance applications, don’t necessarily make good street tires. This is because they are designed to function best at the higher tread operating temperatures than will occur in normal street riding. Also, high-adhesion racing slicks lacking rain grooves of normal street tires may perform poorly in wet riding conditions. 8. Consider tread pattern in selecting tires because the tread pattern, the size and positioning of rain grooves affects how well the tires perform under the diverse road conditions encountered out on the road.
Monitor the condition of your tires carefully. Bulges in the sidewall or tread most likely indicate a ply separation inside the tire and a catastrophic tire failure could be the result. External damage such as cuts or cracking in the tread or sidewall should be checked out; while so-called “dry cracking” in the rubber of the sidewall may not indicate deeper tire damage, a split in the rubber down to the cord in one spot may indicate impact damage inside the tire. Check the rim for deformation or cracking if this type of damage is present. 10. The old saying is that “the tire doesn’t carry the load—the air does.” The point there being that maintaining proper tire inflation is crucial to proper performance, tire service life and safety. Under-inflated tires overheat, are more prone to blow-outs, sidewall failure and premature wear. Similarly, over-inflated tires may fail prematurely and wear improperly. Whatever you ride and wherever you ride, tires are the thing hooking you up to the ground, so take good care of them.
Check your motorcycle tires before every ride, and be careful out there!I recently posted a couple of images showing what I’ve learned about modeling a motorcycle tire that’s subdivided. In this screencast, I’ll show you the best way to handle the creation of a curved object that doesn’t subdivide well. The trick is to subdivide first and then do your other transformations. Let me know if the video is confusing, helpful, too long, not long enough, etc. My bike has a deformation in the rear wheel, almost surely not due to the rim. At some point the tire has a "valley", causing it to bump instead of rolling smoothly. I'd like to understand if I have to replace the tire and/or the tube. I checked the tube and it seems alright, I put it on recently and since then the wheel has become wobbly though. Both tire and tube are 700x35 mm, and they should be the right ones for the bike, since the tire is the original one. Update: I've "played" with the tire, deflating and re-inflating several times trying to get it seated properly.
Now instead of a "depression" there is a sort of sideways deformation. Also in this case the rim looks straight but I can't get the tire to sit right. I tried to put it in place in any way I could think, what am I doing wrong? I've found the problem I didn't notice it before, but the tyre was worn out on the side, and the supporting structure was deforming. I solved the issue by buying a new tyre. tire wheels repair innertube It's hard to tell from that video - a side view would have been more useful. From what you say it seems the rim is actually round in both planes - it doesn't wobble side to side or up and down as it rotates, so it's not that (but I can't see the rim in the video so I don't know for sure). If the problem is the tyre it will be either because the tyre is not seated properly, or it's defective/worn out. But that sort of dip is unusual for a worn out tyre - normally they bulge (then pop). If the tyre isn't seated properly you'll normally be able to see it when you look at the side of the tyre.
Where the dip is the normal markings on the side of the tyre will dip in too, meaning the bead has been pulled in on the rim rather than being pushed out against the sidewall/braking surface. If you're lucky that will have happened because the tyre wasn't installed properly. This is probably only on one side of the wheel, so check both sides. If it's on both sides probably the tyre is the wrong size for the rim, or you may just be particularly unlucky and have a slightly oversize rim and a slightly undersize tyre. To fix, mostly deflate the tube, then work round pushing the bead in on the rim as though you were about to remove the tyre. Then pump the tyre back up slowly until the bead pops back against the rim. When this happens stop pumping, and make sure the bead has popped back all the way round. if not, work the tyre with your fingers where it hasn't popped - just squeeze the tyre in with your fingers. The movement should be enough to seat the bead properly. But if it's a size problem you will need to buy a new tyre.
If the size should be right but isn't, try a different brand of tyre. Some manufacturers are known to make "tight" tyres (slightly undersize beads), others do the opposite. Be aware that it is sometimes possible to put a 700c tyre on a 27" wheel (700c = ISO 622, 27" = 630 or so. ISO is roughly diameter, so the difference in circumference is 25mm or about an inch). It's very, very difficult to do, and shouldn't be done at all. If you're unlucky, you have one of the weird size wheels that's almost a modern size. Sheldon Brown discusses wheel sizes here If the problem is the tube it'll be slightly harder to detect. Tubes are not every strong compared to the tyre, but if you somehow tie a knot in the tube that will affect the shape of the tyre. The most common problems here are a twist, which basically turns the tube into one of those balloon animals; and getting folded back on itself. The fold usually happens when the bike is ridden with the tyre very under-inflated or flat. The whole tyre rotates slighting on the rim as you brake or pedal, but the value stops the tube rotating with it.
Until it breaks off, anyway. So you get a stretched part of the tube, and the other side of the value all the slack collects and folds up. When you re-inflate the tyre there's wobble like in your video. I describe that first because it's easy to check and fix. Deflate the tyre, pop it off, and if there's a big lump of folded up tube next to the valve, there's your problem. Often you can tell just by deflating the tyre than pressing down around the valve. Had exactly the same problem in a 700 x 350 Duro tyre after repairing a puncture and could not understand why the back wheel wobbled so much. Adjusted the spokes for centering the wheel, checked that there was no tube twist, all to no avail. There was however on close inspection about a ten inch point where the Tyre looked as though it was "blown" out just a little and I though that maybe over inflation could have been the cause but I never exceeded 60 lbs so I concluded that wasn't the answer. The answer was that the tyre as explained above had not seated properly and so I deflated the tyre again, checked for twisted tube but this time on assembling the wheel doused the tyre beads with plenty of soapy liquid.