Modern Buddy

Hi, I have a question. After a small accident I had to replace the front tire on my Buddy 170. I now have the factory 100 - 90 - 10 white wall tire on the back and a new 90 - 90 - 10 tire in front. I didn't realize it was a different size when I purchased it. After riding it for a few minutes yesterday after changing it, it just didn't feel right. It seemed a little shaky. I am very new to riding and the scooter has been in the garage for two weeks. So am I just being paranoid or could the different sized tires be an issue? Thanks...

It could be the tire, or maybe you bent the rim. Take the wheel off and set it up on something that allows it to spin freely. Look at it from every angle while it's spinning. If it appears to be wobbling in any dimension, it's bent.

We replaced the rim as well.

Sorry, I should of added that.

The different tread patterns on the different tire brands can affect handling too. Generally you want matching tires of the same brand on both front and real wheels.

I've been told by several people to keep the same tires on both wheels or it usually gets wonky.

I'll be sad to see my whitewalls go, in the next 1000 miles, it'll be time to swap .

Not entirely true that the treads have to match. Some specific tires are intentionally made with a different tread for front and back. What is the brand of the front tire? Some inexpensive makes simply have a weak sidewall and don't work out very well in my experience.

It could possibly be that the wheel needs to be balanced.

Who mounted the new rim and tire?

First thing is to make sure it's inflated to 30psi.

It's true some tires are intended to run different treads front and back, but odds are that's not the case with your whitewalls. If they're different brands with different tread patterns, it might cause some handling wonkiness.

Then I'd check for balance. Most small scooter tires, if mounted properly from the get-go, don't need balancing the way car tires do. If it's unbalanced, you'll most commonly feel a vertical "bounce" or like the tire has a lump in it.

If you replaced the tire yourself, you can check for this by removing it and bouncing it up and down several times on a flat surface. If it's unbalanced, it will bounce at an angle.

My mechanic never balances my tires and it's never been an issue, but he's changed thousands of scooter tires and can mount one perfectly in the blink of an eye.

It's not by much, but a smaller front will pitch you slightly forward. If it were me, I'd either get a new rear to match the front or vice versa.

Thanks for the advice...

The tire was mounted to the rim by a genuine dealer. But, my dad changed the bearings and seal over from the damaged rim.

I tried driving the scooter again today. At higher speeds it has a tendency to sway left and right. And, On curves it doesn't feel nearly as stable as I remember. It really doesn't seem safe to be on. It wobbles...not constantly, but every mile or so I would have to steady it out of a wobble. Could that be caused by the tire difference, poor mounting/balance or could this be fork damage? I'm really worried that it may be something more severe than the tire.

Did the dealer check out the whole scoot or just put the tire on the rim?

Could be a bent fork. Might also be that the wheel's just not properly mounted. Was it torqued on?

Cheshire wrote:It's not by much, but a smaller front will pitch you slightly forward. If it were me, I'd either get a new rear to match the front or vice versa.

This^, by going to a smaller front tire you messed up your scooter's rake and possible trail. With the smaller front tire your scooter will have less stability and react quicker, a bad combination that could lead to a tank-slapper. As much as it sucks you should go get a new front tire, your scooter will be much safer and easier to ride.

At least that is my take.

A 90/90/10 is only about .35" shorter than a 100/90/10, right? I don't think that will make such a dramatic difference.

Even though the difference seems pretty small it could still affect handling. I believe the OP needs to get right size front tire, I think that would fix it. But even if it doesn't fix the problem it eliminates a variable and might make it easier to figure out what is wrong.

ericalm wrote:A 90/90/10 is only about .35" shorter than a 100/90/10, right? I don't think that will make such a dramatic difference.

Even seemingly tiny changes in bike geometry can make huge differences in handling. Just take a look at mountain bikes for proof. Even a 1/2 degree difference in head tube angle (rake) makes a HUGE difference in handling and feel - in having confidence or fear in handling.

I would have it thoroughly checked out by the dealer that replaced your tire and rim. This does not sound OK or even safe.
A "small accident" could cause a lot of damage if things collided just right (or just wrong).

One quick thing to check: See if the tire was mounted correctly. There is an arrow on the sidewall that lets you know how to mount the tire. The arrow should point in the direction of wheel spin. I doubt that this would be enough to cause the symptoms you are describing but it's one more thing to check.

The wheel wasn't Torqued. We couldn't find the torque wrench.

The dealer didn't actually inspect the scooter. He just seen the pictures of the damage and the rim and tire. I'm going to make arrangements to take it to the dealer soon. I would have already, but I live almost three hours away and I don't have access to a trailer. I really didn't anticipate anything this serious happening so soon. The scooter has 300 miles on it.

Thanks everyone, I really appreciate your help.

cV wrote:The dealer didn't actually inspect the scooter. He just seen the pictures of the damage and the rim and tire. I'm going to make arrangements to take it to the dealer soon.

This does raise a different question. Yes, there certainly could be a tire issue such as underinflation, out-of-balance, wrong tire, etc. But, about this accident that bent the rim? Are you now running a new rim? Is it true and balanced? How did you determine that there was no damage to the front fork? A number of other kinds of front end damage could cause the problem you are describing. Sounds like someone with experience needs to inspect the bike.

So there's a chance you may have a bent fork or that the tire's not mounted right. Or… maybe something else.

What happened in the small crash?