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Tillerman6

Choosing a new front tire.

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Some of you guys could help me out a bit if you will. I have decided to convert my trail bike to a trials bike, so I ordered new fenders and am fabricating my own front fork mounting brackets.

The bike originally came with a 2.75 x 21 Bridgestone tube type tire on it, but that one is long gone. What I need to know is what is the overall width of some of the2.75 x 21" trials  tires out there now.?

The tire on my front right now is a 3.00 x 21 knobby, so it is almost touching the inside of the new fender .I think the trials tire will be a bit narrower, but different brands are different sizes even though they all say 2.75"  x 21" or what ever.  I need the measurement OVER the knobs, not the body of the tire and the brand/model number.  There doesn't seem to be any actual dimensions available anywhere of actual mounted tires after they are inflated so that I can tell which one to order.

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You should order REAL trials tires. Dunlop 803 GP or Michelin competition trials tire. There is a few more brands, but not worth talking about. If you got a 3.00 Knobby on it, a trials 2.75 will fit.

Edited by lineaway

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look maxxis trialmaxx. They are good crossover tires.

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Don't know what bike you have, but if you want to have a proper go at trials:

1. Only consider Michelin, Dunlop or IRC

but much, much more importantly

2. Do whatever you can to get a trials bike.

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On 5/14/2019 at 7:15 PM, lineaway said:

You should order REAL trials tires. Dunlop 803 GP or Michelin competition trials tire. There is a few more brands, but not worth talking about. If you got a 3.00 Knobby on it, a trials 2.75 will fit.

From just a little research I did just now, the only 2.75 x 21" tires made for trials are made by IRC.  If you know of any Dunlop 803 GP's or Michelin competition tires that are sized in inches, that would be good to know.

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9 hours ago, cleanorbust said:

Don't know what bike you have, but if you want to have a proper go at trials:

1. Only consider Michelin, Dunlop or IRC

but much, much more importantly

2. Do whatever you can to get a trials bike.

I have a TY 250 which had knobbies and a fat seat on it. The front fender was mounted high up under the triple clamps. All this is being changed out in favor of trials riding. wish me luck!

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On 5/14/2019 at 7:15 PM, lineaway said:

You should order REAL trials tires. Dunlop 803 GP or Michelin competition trials tire. There is a few more brands, but not worth talking about. If you got a 3.00 Knobby on it, a trials 2.75 will fit.

By the way, I'm making my own front fender brackets (long story), and I have a brand new TY style front fender to mount.  How much space should I have between the tire and the inside of the fender?

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On 5/14/2019 at 7:15 PM, lineaway said:

You should order REAL trials tires. Dunlop 803 GP or Michelin competition trials tire. There is a few more brands, but not worth talking about. If you got a 3.00 Knobby on it, a trials 2.75 will fit.

Lineaway,

I don't know if the new metric sized tires will fit the english 2.75x 21 front rim.  The Dunlop 803 GP seems to only be available in metric sizes ?

11 minutes ago, lineaway said:

https://www.splatshop.co.uk/michelin-x11-trial-comp-front-tyre.html

 They are still 275 - 21 even the metric marked tires. If you want the smallest front tire, that would be the Dunlap 803 GP. The ty front fender mounted to the forks, no bracket.

Lineaway, I'm in the states and it's good to know that the metric marked tires are the same thing.  Your link is showing a fairly low price too, so I will check out the shipping prices and see if that still makes sense.  The michelins here in the states are only showing the metric numbers for some reason. Kind of confusing.  Will do some calling around tomorrow. Good info and my "brackets" are special to the forks on this bike. They mount right to the fork legs to accomodate the TY style fender, but the fork legs on this bike have no mounting boss for the bolts from the fender, so it's off to the mill and the lathe making lots of aluminum chips to make something that will do the job. Not the easiest trick I've ever done either! But it beats buying more forks!

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11 hours ago, cascao said:

look maxxis trialmaxx. They are good crossover tires.

Not looking for a crossover tire, just for trials use, but thanks for the input.

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Apparently there are two models of Dunlop 803 series tires. there is the straight D803 and the D803GP for about $20.00 more. So due to my size limitations and the advice on here, I went ahead and ordered the 803GP  tube type model.  This will help me finalize the position of the new fender so I can drill the new holes in the exact spot they need to go and also make sure there is enough room for the expansion chamber and some mud on the tire.  What would be a good height above the tire  front and rear?Thanks for all the good advice!

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From what you have written it sounds like you have non-standard forks, so to know how high you can have the mudguard above the tyre, you will need to test where the tyre OD is with the forks fully compressed. Standard TY250 forks don't have much room between the tyre and the lower triple clamp and yours with different forks might have even less.

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On 5/17/2019 at 7:57 PM, feetupfun said:

From what you have written it sounds like you have non-standard forks, so to know how high you can have the mudguard above the tyre, you will need to test where the tyre OD is with the forks fully compressed. Standard TY250 forks don't have much room between the tyre and the lower triple clamp and yours with different forks might have even less.

You have raised a good point about the clearances behind and above the new fender that I had not thought of. .  Fortunately, the new brackets are somewhat adjustable up and down the lower fork legs so the fender can be adjusted up or down about an inch or so,  and also the fork tubes themselves are about an inch and a half longer than they need to be. These are TYB forks and the last 2 inches at the top of the tubes looks to be a separate piece, although they have resisted my best efforts to unscrew them. I can't tell if the triple clamps are Yamaha, or they have also been swapped out for the TYB.  I will include some pictures here and maybe you can tell if they are Yamaha triple clamps?  I had to replace the lower balls and races inside the center post, and I ordered Yamaha parts for that and they fit the frame and the center post perfectly, so i think it's just the fork legs and front wheel assembly that was swapped out. ?

TyB forks 024.JPG

TyB forks 025.JPG

TyB forks 026.JPG

TyB forks 027.JPG

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Your triple clamps are TY Yamaha. Your fork sliders are MX or YZ Yamaha and your brake backing plate is MX or YZ Yamaha. The lines on the fork tubes are there as a reference for where to clamp them on the bike that they originally came from. If they are longer tubes than TY250A then they are not TY250B, because all the TY250 twinshocks have the same length fork tubes. I would expect that the fork tubes are also off a MX or YZ Yamaha.

To maintain the standard TY steering geometry you should set the tubes so that the axle is in the same position as it would be with TY forks. If the travel of your forks is longer than TY forks you may need to fit travel limiting spacers to the damper rods, to avoid the mudguard or tyre hitting the lower triple clamp.

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