Replacing standard wheels

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Cherie
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Replacing standard wheels

Post by Cherie » Thu Apr 30, 2009 10:09 pm

It's a very common question and easily the most popular modification that can be done to a car.

There are some things to take into account, such as the size of the wheel you want, the size of the tyre, the fitment etc. so I'm going to try and collate all the necessary info into one post.

Standard Puma wheels specifications:
Wheel Rim diameter = 15"
Stud PCD = 4x108mm
Offset = ET34
Tyre Size = 195/50 R15
Wheel width = 6J (6")


Specifications for 16" wheels:
Offset = between ET34 and ET38
Tyre size = 195/45 R16

Specification for 17" wheels, 7" wide:
Offset = between ET34 and ET38 (but ideally either ET35 or ET36 due to rubbing issues)
Tyre Size = 205/40 R17

Specification for 17" wheels (FRP) 7.5" wide:
Offset = ET25
Tyre Size = 215/40 R17

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Many people decide to lower their car as well as increase the size of the wheels. As even though the size of the wheel has increased, the profile of the tyre has decreased, and so will still sit in exactly the same place in the wheel arch. So it'll still look like a moon buggy - just a moon buggy with bigger wheels!

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Terms explained:

Stud PCD:
PCD stands for Pitch Circle Diameter. In laymans terms, this the measurement of the distance between the studs the wheel is attached by. Pitch Circle being the circle that passes through the centre of every stud, and hence the measurement is the diameter of that circle. 4 is the number of studs.

Different car manufacturers use different diameters as standard.

Offset: ET##

This is the measurement of how much the part of the back of the wheel that sits on the hub varies from the centre line of the wheel.

Image

A positive offset of ET34 means that on yhe standard Puma wheels (both props and 9 spokes) the back of the wheel is 34mm away from the centre line.

If you have a set of wheels that have a higher offset, the inside edge of the wheel will sit further into the wheel arch, and this is why they rub on the arch lining.


It is also very much worth remembering that if you've also lowered the suspension, that the front wheels may rub on the top seam above the wheel, and worst case scenario, you'll end up with a cut tyre.

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Useful website:

By inputting your current and modified setup you can see visually and described differences to see if they'll fit:
http://www.willtheyfit.com/" onclick="window.open(this.href);return false;

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Always remember to inform your insurance company if you have changed your wheels on your car from standard.
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