Wheel Rim Sizes

Wirral_guy

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Are all Alloys exactly the same size? When I say this I mean are the lips\edges always exactly 16" or 17" etc whether from Mercedes, Ford, BMW or after market makers or do they all vary to some degree?

I know that you can fit a number of different widths of tyre to a particular size but have never known if the actual diameter varies so am curious.


Dave
 

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Wheels for the MB are quite critical, they are hub centric and do not center on the wheel bolts. The ET plays a big roll an all cars after 1999 where after that date they all have ESP.

You can fit different diameter tyres but when you do so you compensate by changing the height of the side wall so that the running diameter stays the same. this figure is the second one on the tyres So on a wheel and tyre that use say a 245 x 45 x 17, the 245 is the width of the tyre, the 45 the height of the side wall, that is a percentage of the width, and the last figure the diameter that is common to all cars and wheels. the ET is the distance from the center axis that the wheels sit either in or out
 
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Wirral_guy

Wirral_guy

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Thanks Malcolm but it is the actual diameter of an alloy wheel that I am more interested about. Not for a particular car or anything just a thought I have had :idea:

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Then all the same as the tyres come in the different sizes and they will fit any cars wheels
 

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My car came with a 245mm option tyres and alloys. What is the advantage of this over standard width? Can I fit standard width tyres to these alloys?
 

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My car came with a 245mm option tyres and alloys. What is the advantage of this over standard width? Can I fit standard width tyres to these alloys?

You can fit the same tyres to wheels that a ½ inch wider or narrower wider tyres give more grip in the dry, but less in snow.

Take a look in this chart and you will see where different widths can be fitted to wheels of the same sixe and vice versa

http://www.alloywheelsdirect.net/information/fitting_chart/mercedes-benz
 

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My car came with a 245mm option tyres and alloys. What is the advantage of this over standard width? Can I fit standard width tyres to these alloys?

You can fit the same tyres to wheels that a ½ inch wider or narrower wider tyres give more grip in the dry, but less in snow.

Take a look in this chart and you will see where different widths can be fitted to wheels of the same size and vice versa

http://www.alloywheelsdirect.net/information/fitting_chart/mercedes-benz
 

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You can fit the same tyres to wheels that a ½ inch wider or narrower wider tyres give more grip in the dry, but less in snow.

Take a look in this chart and you will see where different widths can be fitted to wheels of the same size and vice versa

http://www.alloywheelsdirect.net/information/fitting_chart/mercedes-benz

Mea culpa! I should have said my car is fitted with 225 not 245 tyres. So you are saying that using my present alloys I couldn't swap back to 205 wide tyres as they are 20mm narrower?
 

survey

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Mea culpa! I should have said my car is fitted with 225 not 245 tyres. So you are saying that using my present alloys I couldn't swap back to 205 wide tyres as they are 20mm narrower?

I think I am having one of those senior moments! Maths has gone out of the window! 225 less 25mm DOES give me the option presumably to go back to 205mm tyres on these alloys then. Would you stick with the 225mm's or go back to 205's?
 

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225mm tyres often fit a 7.5j wheel and a 205 fits a 7j wheel

I hve gone down 20mm on my tyres on the width as they were £100 cheaper

225 tyres also fit a 8j rim so there is some flexibility here
 

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1. Am I going to actually notice any difference (apart from the price) by dropping back to 205's?
2. Would it affect a trade-in price as the car came with the OE wider tyres? Obviously the option alloys would remain.
.3 Also I would be renewing the rears before the fronts. Will it be OK to have 205's for a while on the rears whilst still using the 225's on the front until the fronts need to be replaced?
 

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If you go back to 205 tyres, then you will have to up the profile number by one to 55 as apposed to the 50 that you have now, and no it will not matter about changing them now
 

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There won't be much discernable difference between the 225 or 205 tyre. There may be a little more road noise with the 225, but you will get better grip.
The 205 may be slightly quieter, and give a better ride.
Don't forget the aspect ratio changes when you change width. If you had a 225/50/15 tyre then you would want a 205/55/15 if you wanted to go to the narrower width. The aspect ratio figure is given as a percentage of the width.
You would increase it slightly to achieve the same rolling radius.
 

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