Modern Vespa

Now, before you answer, I DID read the owner's manual.
I know that the recommended inflation pressures of the tires on my GTS 300 machine are 26psi in the front; 29psi in the back. higher in the back if you're carrying a passenger.

I replaced the rear tire on my LX150 at around 3K miles, I note that the tire rims had cracks. My dealer had recommended that I keep that inflated at 30 psi front and 35 psi back regardless of what the manual said. And I did maintain it at that. I check pressure on cold tires at least once a week.

Granted the tires are smaller on the LX150 than the GTS 300. So I guess my topic of discussion is: should I be keeping to the 30/35 rule with the GTS?

How often should I be checking tire pressure (Yes, I know from my MSF course that I should be performing T-CLOCKS on my machine every time before I ride, but it's a pain in the ass on the 150, as I have to bend the rear valve stem slightly to get my digital pressure gauge on) It's not so bad on the GTS, but you lose a tiny bit of air each time you do this.
My riding on the GTS is going to be mostly highway, rather than urban, as I am keeping my 150 as the 'food shopping/errand" machine.
I know that underinflation is more detrimental to tire wear than the opposite. but I would like to get better mileage out of my tires than I have been getting thus far.

Discuss? <ducks>

Judging by your picture in your avatar, you're not a large person so 26/front-29-rear is probably best for tire wear and handling on your scooter. 30f-35R on your other scooter is way too much for a single rider who doesn't weight 275+ pounds.

I check the pressure on our scooters once a week. If I was going on a long trip, I would also check them before I left and along the way (always cold)

Hi,

I was at my dealers recently and was discussing tires with a mechanic there. I was saying I like the tires on the 300 but they feel softer in hot weather. He advised to use 30 -35 psi, he said the tires would last longer. So I tried it. They felt over inflated, like you are only using the very centre of the tire, rather than the middle third. So I changed them back.

I check them about once a week, or before a long journey.

Marc

I think mechanics like to recommend higher than manufacturer suggested tire pressures because they assume that we won't check our tire pressures and thus it would take longer before they get so low that they would be dangerous to ride on.

Ahh thanks Benito, that makes sense now. (penny dropping)
I was telling him how lazy I can be at times.

I noticed that my mechanic was always putting too much pressure in my tires when I would check after a service. I also noticed that my rear tire is really really worn in the centre, a very narrow strip, I think that is because of the over inflation. I don't think I'll go much above recommended in the future.

I used to run 30/35 pressures on the first GTS that I bought. I am 6'1"/225 lbs and thought I should run higher pressures than the ones recommended by Vespa to compensate for my weight.. WRONG!...............the rear tire wore down to the cord in the middle of the tire in only 2000 miles and showed hardly no wear to the sides of that three inch patch that wore prematurely. I rode that scooter 90% in the mountains and on country roads that require a lot of leaning so the tire was obviously over-inflated. I went back to 26/29 and got much better wear on the rear tire.
The front tire didn't exhibit any problems from running 30psi but the ride was much softer with 26psi so I'm leaving mine at 26/29. YMMV

Cracks in your rim? Oiy. If they are indeed cracks in the rim and not just damage to the powdercoat, you really should replace them. To my mind it's just not safe. What's not to say, you hit a bump hard enough, or in the right spot that those stress cracks don't expand, and cause a blowout or worse? Hate to be a worrywart but you might want to ask that dealer about it again.

As to checking tire pressure...

Always do it when they are cold. Otherwise you'll just be over inflating them, and the pressure rises a bit once the tires have been moving/rolling down the road.

Even driving to the gas station just a couple miles down the block is too much.

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If you really want to be retentive, follow the 10% rule...fill them up cold, ride it like you like you normally do...if it's more sporty, then find a curvy road and go nuts; if it's more cruising, then do that...then in the middle of your particular ride, check your tire pressure again.
It should increase by 10%.

If it's higher than 10%, you need a little more air pressure (add a pound or two and repeat the process the next time you ride) as the tires where too soft/flexible, and built up more heat, which increased the pressure too much.

If it's less than a 10% increase, take out a pound or two of air pressure, as the tires started out too firm, and didn't build up enough heat to be flexible/compliant.

Mind you, this was always for my track bikes, and just let you know what pressure worked best for you + the bike + the new tires + track conditions, but should still work just fine here.

I run mine on my GT at 30 and 34 and have done 9500 kms on Perrellis, got about 9,000 on michelins and 8,500 km on SAVAs all rear tires, riding mostly rural roads, or secondary highways at speeds between 80 and 100kph. Sava have a maximum pressure written on the tires of 41, I think that is higher then most of the other brands that are available so i would assume that they also perform at their best a little higher then others. Personnally 26lbs seems low to me but a couple of pounds either side of 30 shouldn't endanger you or make a marked difference in wear. Piaggio used to recommend 17 and 20 on their old tube tired scooters(Ps and PXs) but most people who run them today with modern threaded tires will suggest 20 and 25.

I mis-spoke, as it were, the cracks were in the tire's sidewall, not the rim (which would be the wheel). And reading the previous posts, I am believing that it was due to over-inflation. I also had excessive center wear on the rear tires.[/i]

Thanks for the input all.
After a ride I just took (literally) ten minutes ago, I was going up the 101 here towards San Mateo from Palo Alto.
There were some strong cross-winds, as is usual this side of the Bay. I was going about 60 mph.
I noticed that my front tire felt quite 'wobbly' in this cross-wind and it was hard to maintain a steady center lane position. I kept drifting to the right, and I don't believe it was due to the road surface. It also felt 'bouncy'.
I checked pressure in my front tire at my destination after the vehicle had sat for 25 min. And it was definitely over-inflated at 35 psi. I dropped to about 27 psi and rode it the same way back. The rear was at 29 psi, so I let it be.
Much better handling characteristics. I don't think I will ever inflate my tires above 30 again. And I will definitely keep the front around the 20-25 psi zone.
I will check them again in the morning when the tires are stone cold.