Hi,
I'm looking to buy Ohtsu radial tires for my ds650. My concern is about how fast that they wear out. I can't afford to buy tires too often. I would appreciate any information.
Thanks,
Schoolboyrowe

P.S. Hightower said that it took the twitching out of the front end. Has anyone else had that same result.

 

If you what handing go with the Ohtsu.If you what wear stay with the stock tire. There is night and day difference between them.

Thanks

 

I've had the Ohtsus for only a few months, so I can't comment on how fast they wear out. My only advise is to stay off pavement 'cause they are soft and pavement will eat them up in no time. This soft rubber is part of the reason they get such good traction, combined with being radial.

As far as the twitch goes, there seems to be quite the contraversy over that around here. With the toe set around neutral to 1/8" out (with my weight on the seat), combined with the Ohtsu radials front and rear, the twitch is only barely present at extreme speeds, and non-existent anywhere under 60. I'm 6"-8" tall, weighing in at 235lbs., so this probably helps too. I can't promise your bike will handle as well with you on it, but you will notice a great improvement. Even if you still have high speed twitch, the traction and steering response will be worth the purchase.

From what I've read, the Baja a-arm geometry is the same as the DS, even though they are made different, and the handling improvements the magazines boasted about are attributed to the tires. I do want aftermarket a-arms eventually, because I'm all about getting things tweeked perfectly for me, my weight and style.

Going from a 21" tire to a 22" tire in the front adds caster, which too little caster is the cause of the twitch, so the bigger the difference between front and rear tire size the better. The traction helps tame the twitch too.

 

I got them on my DS,and I love them.It's one of the best modes I have done to my DS.It DOES stop the high speed twitcy handling on the DS,for sure.

 

I to have them. They are a good upgrade for the money.

 

3TV - are you sure that your suspension and toe is set the same on your DS as your Baja??
If so, then the geometry is definitely not the same.

 

Hightower,

You have seen a Baja in person, right? When I saw it, the first thing I noticed about the A-Arms is that they have a slight bend in them near where the shock mounts. Did you or anyone else notice the same thing? I suppose it's possible that the geometry could be the same between the A-Arm with the slight bend and the one without, but there has to be a reason for that bend. It seems to me that may be the key.

 

Blackhawk - The element of geometry on the DS front end that contributes to twitch and wander is caster. Caster would not be effected by this bend.

I read, in a magazine article, and I don't remember what magazine, but it said that a Bombardier rep said that camber and caster remain the same, and the only difference is a more economical means of manufacture, which makes them look different. Earlier in the same article it said the Baja handles better for two reasons - tires and new a-arms. It actually contradicted itself. I really would like to know if the geometry is the same, just for the sake of curiosity, but haven't been able to get a solid answer yet.

Can somebody with a Baja, a level, and a protractor, measure the caster on their Baja and tell us if its the same 5 degrees as the DS?

 

I'm not sure of the technically appropriate way of measuring caster. There are instruments made for it that the car mechanics use, but I have a decent understanding of what we're looking for, so I think it should be able to do on a quad relatively easy with a protractor and level.

The wheel needs removed, and the hub needs propped up at normal ride height, cause things like tire size, suspension setup, etc. can change the caster angle.

On the left side of the quad, looking at the ball joints, you will notice the upper set back further than the lower. I'm thinking you can measure caster by positioning the level at the horizontal plane of the lower ball joint, set the protractor on the level at the center of the lower joint, and measure the angle between the vertical plane of the lower joint, and the center of the upper joint.

The caster angle of the DS is said to be around 4 to 5 degrees - a little inconsistent from bike to bike. Ideal caster is said to be somewhere between 7 and 9 degrees. Moving the upper joint back achieves this. The less the caster angle, the more sensitive the steering, and the DS is a little too sensitive, which is where the infamous twitch comes from.

I'm actually considering putting my a-arms in a press, very carefully and precisely putting a slight bend in the uppers to achieve 8 degrees caster, and seeing how they do. If I screw them up, I'll have to get some new American Star arms, and then I can justify the expense with the old lady - "I have to Mandy, mine got bent!"