Tire Pressure Questions

[zeus17]

so this may have been asked a lot already,but for give me if i ask a very stupid question.

 

i want to know how to compute the right tire pressure for my weight and suspension i guess.

 

the tricky part is my bike is considered a small bike in your country ( i Live outside US),150cc,naked bike.

i changed tires over to something bigger since my actual mags can ccomodate something big.

 

here are a few details

 

rider weight is 120-130ish pounds

150cc bike,

3.0 rear mags,with 130/70 tire

2.95 front mags with 100/90 tires

 

any inputs will be appreciated.

 

stock tires were

110/80 at the back and 90/90 in front,recommended psi are 33....

 

 

[Hotfoot]

Definitely not a dumb question and I don't know if there IS a calculation for that - maybe our resident tire expert can help.

 

Do you have any idea of the weight of your bike? What sort of riding are you doing, street or track? What type of tires, road use or track use or racing slicks?

 

The best thing to do is to ask the tire vendor, if possible.

 

For what it is worth, the lightweight 125cc race bikes (which are likely lighter weight than yours, if yours is street legal) run similar size tires and usually start with about 25psi cold (27-28psi hot) for both front and rear, for racing use. For street you'd probably want it a big higher.

 

This is a guess (not a calculation) on my part, but you could probably start at around 30 psi front and 28 psi rear (cold pressures) and see how the bike feels and how the tires wear. Pressures too high would probably give you a harsh ride and a feeling of not enough grip, if the pressures are too low you might notice the steering feels sluggish.

 

If you think your bike weight is similar to a Ninja 250, you could search the web for tire pressures for those - the tire size is similar and they are commonly used for racing, and for those race bikes the weight is lighter and would probably be more comparable to a 150cc naked bike.

[ktk_ace]

I would like to add that if your 150CC bike has a wheelbase of LESS than 1370MM , changing tires different to stock sizes can have huge effects on the handling alone ,

 

and most of the time detrimental if you dont know what you are doing.

 

Over/understeer and stability issues could arise easily.

 

happy reading:

http://www.risingsuncycles.com/bikespecific/suspension.htm

 

PS. The ninja 250R has a 1400MM wheelbase and the CBR250 1370.

[zeus17]

@hotfoot

 

weight yes,

http://www.motorstar.com.ph/products/xplorer-z150

 

Dimension L x W x H 2040 x 755 x 1045 Wheel Base 1330mm Min. Ground Clearance 170mm Net Weight 130kg

 

 

the bike is mainly for road use,track is something that is every once in a while thing but i have not tried yet,plus the lack of someone to teach is one thing or atleast coach...

 

the tires are mostly road tires not slicks,

as for the vendor ,no information on the site,

 

this is the tire

http://fdrtire.com/product/view/2

Size Type Load Index Max Load (kg) Speed Symbol Max Speed (km/jam) Rim Width Overall Width (mm) Overall Diameter (mm

 

130/70-17 TL 62 265 S 180 2,75 ; 3,50 ; 3,75 129 618

 

nothing really recommended psi.

 

and as far as tires sizes,the guy where i bought the tires suggested those sizes, ,i did not know this forum nor anything about bikes,still on the process of learning ,watching videos and reading articles,)

 

@ktk_ace

 

thanks for the link,,thou my rear suspension is adjustable i think,no one here seems to know how to fine tune it to my weight,still reading articles about that too...so i can DIY i guess,but front end is not.

 

but the link is helpful,would you mind if i ask here again if i dont understand something?

 

 

i would apologize in advance, we do have safety seminars here,in which i did attend but nothing as extensive as what i read about or even watch at keith"s twist of the wrist 2......

 

currently...

 

from stock

modifications made by the dealer was lowered the front 1 inch to accomodate my height, 5"4"

and just the tires...

[Stroker]

We run between 30-32.Lower in the monsoon for grip.