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@luckyguy avatar
UTC

Hooked
GT200 / ET2 Kitted
Joined: UTC
Posts: 193
Location: Louisville, Colorado
 
Hooked
@luckyguy avatar
GT200 / ET2 Kitted
Joined: UTC
Posts: 193
Location: Louisville, Colorado
UTC quote
Hello Fellow enthusiasts. As usual, thanks in advance. This is absolutely a wonderful resource and I value all of your opinions, experience and knowledge.

So my lovey GT200 (Victoria) and I have been getting to know each other. Among other things, I am preparing to do my first oil change (my first, not hers) and plan to take great care of her.

On to the question/issue; *All of these readings are cold tires. If it matters, outside temp was about 50 degrees Fahrenheit.

- I finally got a worthwhile pressure gauge and checked my tires. The plaque on Victoria says it should be 26.5/29.5psi front/back respectively. The Tires themselves say 41psi (max the tire can handle?). I have read here that I should go with what the scooter says and not the tire.

So I checked my tires and the reading on my tires (from new fancy gauge) was at 30/32.

So before taking it out for an afternoon spin, I let some air out ant got them down to about .5 psi above "factory" recommendations. roughly 27/30.

Keep in mind I am an inexperienced rider still learning, but when I was taking curves this afternoon, especially at speeds between 35-45mph, it felt like there was a bit of "wobble" in the front tire as I started to lean into my turn. Not drastic, but noticed it twice. Not the most fun feeling ever. I don't remember this happening before I let some air out of the tires.

Initial googling/researching tells me that this may be tire pressure related.

Questions:
1. Would you think this is indeed related?
2. If so, should I be concerned that the scooter handles better with slightly overinflated tires? Is this a sign that something else is wrong?
3. Is there any dangers with re-inflating the tires to the 30/32 area? Should I not do that? Will I lose grip in corners and such (though a wobble is worse)

Thanks all
@suibhne1 avatar
UTC

Member
2012 gts 300 super
Joined: UTC
Posts: 13
Location: Eugene OR
 
Member
@suibhne1 avatar
2012 gts 300 super
Joined: UTC
Posts: 13
Location: Eugene OR
UTC quote
I have the same question!

When I got my Vespa from previous owner, I thought handling was very wobbly and felt like low tire pressure. I measured it and it was at around 15. Brought it up to 26 and it rides much better now, so the low tire was definitely the issue.

However, even at 26 (30 in the back -- I have a 2012 gts 300 super) the ride is still occasionally wobbly, mostly on turns. So I'm also wondering if I can take the pressure higher than the manual and/or what I should consider when doing so?

I'm also a new PTW rider, but I've ridden human-powered bikes for years and maybe I'm just used to the high tire pressure from that time.
@pigletpilot avatar
UTC

Molto Verboso
Gina, 1965 Vespa 180SS, Bella,1968 Vespa 150 Super, Mia, 2017 Vespa Primavera 70th Anniversary 150ie, Gabriella, 2017 GTS300 ABS
Joined: UTC
Posts: 1885
Location: Hamilton/Kirikiriroa, NZ
 
Molto Verboso
@pigletpilot avatar
Gina, 1965 Vespa 180SS, Bella,1968 Vespa 150 Super, Mia, 2017 Vespa Primavera 70th Anniversary 150ie, Gabriella, 2017 GTS300 ABS
Joined: UTC
Posts: 1885
Location: Hamilton/Kirikiriroa, NZ
UTC quote
I run my GT200 at factory pressures. The front wheel wobble you experience is a "feature" of the scooters, it is pretty obvious around the 50kmh mark but goes away above that. No end of threads about the wobble on here. It was finally resolved in the last couple of years with a change to the front suspension.
Running "incorrect" pressures will adversely affect the wear rate of your tyres. Too high will wear the centre out prematurely generally.
You are right on the 41psi, maximum the tyre is designed to ever take (please correct me if I'm wrong anyone more knowledgeable) but I suspect the scoot could be skittish with that much pressure.
@rjc1944 avatar
UTC

Hooked
Matt Black 2014 300GTS Super Sport
Joined: UTC
Posts: 319
Location: Perranporth, Cornwall, England
 
Hooked
@rjc1944 avatar
Matt Black 2014 300GTS Super Sport
Joined: UTC
Posts: 319
Location: Perranporth, Cornwall, England
UTC quote
My thoughts are - the pressures your tyres were at are only about 10% higher than what you have reduced them to and so won't really affect tyre wear. Reducing pressure has made your handling worse. Put them back to where they were and try them. If the bike rides better then leave them at that. If it still "wobbles" then you'll just have to get used to it.

All that presumes, of course, that your tyres aren't worn out!

Get out there and ride. Enjoy your scooter and stay safe.
@larrytsg avatar
UTC

Ossessionato
1979 P200e
Joined: UTC
Posts: 2665
Location: Lock Haven, PA
 
Ossessionato
@larrytsg avatar
1979 P200e
Joined: UTC
Posts: 2665
Location: Lock Haven, PA
UTC quote
Your tire pressures seem fine to me... you can go a little over on these without too much trouble. Don't go crazy, but a pound or two is no big deal.

And yes, the 41 printed on the side of the tire is the max pressure the tire was designed to run.

Not sure what year your scooter is, but perhaps the shocks need to be replaced. When I first got my scooter, it was over 30 years old, and was running on original shocks. The previous owner never had any issues, but when I had the scoot in for some brake adjustment, the mechanic asked how it cornered. I said it was fine, and he said "it's a miracle you can get around a corner with those shocks". A pair of performance shocks later and I felt very stable and planted.

I know many of us want to be do-it-yourself-ers, but sometimes having someone else take the saddle can give you insight into what's going on.
@cdwise avatar
UTC

Veni, Vidi, Posti
GTS 300, Buddy 125
Joined: UTC
Posts: 8870
Location: Knoxville, TN
 
Veni, Vidi, Posti
@cdwise avatar
GTS 300, Buddy 125
Joined: UTC
Posts: 8870
Location: Knoxville, TN
UTC quote
Not to be personal but how much weight are your carrying on your Vespa? Heavier weight or two up needs more air.

For example on the P series with original tires according to http://www.vespamaintenance.com/specs.html

Tires
Size: 3.50 X 10, front and rear
Pressure (for factory tires)
Front: 17.6 psi (1.23 kg/cm2)
Rear (up to 180 pound load): 25.8 psi (1.8 kg/cm2)
Rear (over 180 pound load): 36.7 psi (2.58 kg/cm2)

According to the factory sticker on a GTS

front should be 28.1
rear tire should be 29 for a single rider and 37.7 two up.

I over pressure my front because it handles better with 29/32-33. Since I routinely get around 10,000 miles on my front tire I'll stick with the pressure that feels best. FWIW, the only time I ever feel a wobble is when the tire pressure gets below 26.
@old_as_dirt avatar
UTC

Veni, Vidi, Posti
2007 GTS
Joined: UTC
Posts: 22448
Location: Harriman, Tennessee, Tn
 
Veni, Vidi, Posti
@old_as_dirt avatar
2007 GTS
Joined: UTC
Posts: 22448
Location: Harriman, Tennessee, Tn
UTC quote
I'll chime in.

first off tire pressure gauges are inaccurate, unless you have a very expensive calibrated one that would probably cost you something over $200 and that has been certified by a lab.

now with that out of the way.

fill your tires to max according to your gauge. ride the scooter over a certain course of say 2 miles. check your pressures. now drop your pressures by 2-3 lbs , ride your scooter over the same course again. do this until you find that same feeling as you don't like as you described. now pump up your pressure to a couple lbs over that and ride the course again.
Do you like the way the scooter handled? if yes nothing more to do but know that pressure on that gauge.
if not keep adjusting the pressure up or down till you like it.

What one person likes for tire pressures is totally different than what someone else like. and these are variables.
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