Yokohama and avon tyre pressure

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Hi to all, I have got a pair of Yokohama tyres and there are 195/45r15 and a pair of Avon 195/45r15 and i dnt know the psi of them. Wats my best bet to do. Can any one recomend any places ring or is there any web sites i am try. Thanks to all for looking Ash

yeah it is for a corsa 1.2 16v Vreg, does that make ant difference. Thanks again ash

Reply to
Corsa_Ash
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Yes, car model makes a difference on these things. I dunno whether the V reg is the same as the current model, it seems to be, though.

The Corsa is designed to work properly with a 23 inch wheel, the wheels you have are 22", basically they are too small for the car.

There does seem to be difficulty with tyre sizing. Probably doesn't help that they mix imperial and metric. It's basically quite simple:

Measuring from, say, the top of the tyre, to the ground, gives the diameter of that wheel / tyre (add a little if the weight of a car is on it, or measure horizontally.) In this case, you want 23 inches, which is a pretty typical size for a medium size car, 3 series BMW, A class Merc, etc.

This diameter comprises the rim diameter - the size of the metal part in the middle of the wheel - and the thickness of the tyre added at both top and bottom.

A 23" wheel can be:

tyre - rim - tyre 5 + 13 + 5

4.5 + 14 + 4.5 4 + 15 + 4 3.5 + 16 + 3.5 3 + 17 + 3 2.5 + 18 + 2.5

Not to put too fine a point on it, the rim diameter defines how much tyrewall you need to add to get the correct wheel diameter.

To find the thickness needed, the tread width number (e.g. the 185 in

185/55.R15) is multiplied by the profile percentage (e.g. the 55, divided by 100) i.e. 185 * 55% = 102 mm or 4 inches.

As this is 4 inches + 15 inches + 4 inches as in the table above, for a 185 tread width, you would fit 185/55.R15 tyres, with 15 inch rims.

Similar game, 13 inch rims need 5 inches of tyrewall = 159 * 80% = 155 or

165/80.R13

Width matters as a factor of sidewall percentage, so wider tyres fit with a lower profile, so long as the wheel rims are wide enough to handle that width of tyre and there is sufficient clearance (wheels cannot stick out past the wings or touch the bodywork inside.)

17 inch rims put you down to 3 inch thick rubber = 3 inches is 76 millimeters: 169 * 45% 191 * 40% 218 * 35% 254 * 30%

You can't get exact sizes, so these are 165 or 175 width, on a 45 profile, 195 on a 40 profile, 215 on a 35 profile, and 255 on a 30 profile.

Since Vauxhall fitted the 17in alloy options with 205/40.R17 this is probably a smarter choice as you can tell the insurance company this is standard equipment on that chassis, albeit on a different model. Same situation with 195/45.R16 (3.5 inch rubber, in that case, with a 16 inch wheel makes 23" total.)

Set the tyre pressures to suit your tastes, there should be a difference in any case between the recommended for town driving and the recommended for motorway driving, so you can see it's only a guideline. If you find you wear the centre of the tread out first, you might use a lower pressure in future. Vice versa for the outer tread pattern wearing out faster. I generally pump mine up a bit higher than recommended because I prefer speed and economy to ride comfort.

If you fit these tyres, the tyre pressures would be much the same as with full size wheels, this isn't really the root of the problems you would create (speedo accuracy doesn't matter much, but the angles of all the suspension arms would suddenly be wrong.)

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Questions

Ok then, well all that helps, but i still dont know the tyre psi, still unsure??? i think its about 28 to 31 psi but really unsure, can any one help. Many Thanks Ash

Reply to
Ashley

I've already answered your question more than once !

What is the STANDARD tyre pressure for your car ?

You need to be runn> Ok then, well all that helps, but i still dont know the tyre psi,

Reply to
Nom

And you need to realise the tyres are too small. PSI is much less of a question, although Nom's advice is basically sound on that.

Apparently >I've already answered your question more than once !

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