Hopefully this can be made a sticky.

Fitting new alloys to your car.

The amount of questions that get asked on here about people getting new alloys I though I would do a bit of a write up to explain what’s what.

What do the numbers on my wheel mean?

Most wheels will have the following stamped on them:

The diameter of the wheel e.g. 16â€

The width of the wheel e.g. 6.5j (The letter, in this case J refers to the shape of the rim. Rim contours are standardized by the Tire and Rim Association, so that tires will fit. This is measured from the inside of the flanges to the opposite side *not edge to edge*)

The offset of the wheels e.g. et35 (the et is the distance from the centre of the wheel to the face of the bolting plate.)

What does offset mean?

A wheels offset is the distance from the centre of the wheel to the face of the bolting plate.

Effectively the offset is also the distance from the centreline of the wheel to the hub face.

Therefore:

If you put a wheel on the same hub with a bigger offset, the wheel will sit further inside the wheel arch because the wheels bolting face will have to move further in to meet the hub.

Alternatively if it has a smaller offset it will sit further out from the wheel arch.

For sports purposes grip would be improved by increasing the width of the wheel (and tyre) and using a smaller offset to allow for the extra width on the wheel in the wheel arch.

What else needs to be taken into account when fitting new wheels?

Wheel Diameter:

This is the size of the wheel, such as 16". Bigger wheels are usually heavier and thus will make your car slower. If you get a bigger wheel than stock, you must get lower profile tires. More on that later.

Wheel Width:

This is the width of the rim, such as 7.5j" or 8j", as if you were looking at it from the back of the car. Wider wheels require wider tires and various offset adjustments. More on this later.

Bolt Pattern:

The bolt pattern of the wheel is key in determining whether or not it will fit on your car. VAG cars have a bolt pattern of 5x100 or 5x112 which means there are five lugs with spacing of 100mm or 112mm. Some cars have 5x120, others have 4x100, etc. The point is, you have to get a wheel that matches the bolt pattern on our cars, which is 5x100. If the bolt patterns do not match, the wheel will NOT go straight on your car.

Hub Size:

The hub size is basically the diameter of your hub in mm. VAG cars have a hub size of 57.1mm. This is important when choosing spacers or hub centric rings. More on that later.

Centre Bore or Hub Bore (on wheel):

Every wheel in the back has something called the hub bore or centre bore. This is the space in the back of the wheel where you hub inserts. It is where your wheel 'sits' on your hub. Therefore, as you can imagine, it is important that the size of the hub bore on the wheel and the size of the hub on your car match up; else your wheel will wobble. If the hub bore on the wheel is too small you will have to pay a lot of money to get the wheels bored out larger. But if the hub bore on the wheel is too big, then there is an option: hub centric rings (Spigot rings). More on this later.

Offset:

The next thing to look at after the size is the offset. The offset determines how far off the hub the wheel sits on your car. A lower offset means the wheel sits further away from the hub, causing it to stick outwards more from the body. A higher offset moves the wheel in towards the body more. Offset is measured in mm, and you may think a few mm here and there don't matter but they do. Move the wheel too far out and you'll rub the arch, too far in will rub the strut. A standard Fabia vRS has:

16x6.5 et35

Spacers:

Often when you buy a wheel, they don’t have the correct offset. If the offset is too low, let’s say around 15, then I think the only option you have is to roll your arches. However, if the offset is too high, spacers can be used to bring the wheel out further from the hub, i.e. decrease the offset. Spacers usually come in increments of mm, but sometimes inches. So if you have a 50mm offset wheel, and you employ a 20mm spacer, you will decrease your offset to 30mm, thus enabling you to use a wheel that would otherwise rub your strut. It is important however, when buying a spacer, to buy a spacer that fits the hub of your wheel. This means getting hub centric spacers which are 5x100, for sale on eBay all the time.

Adaptors:

HUB/PCD adapters give the possibility to fit wheels with a different bolt-pattern/centre bore to your car. This means if you wanted to fit Porsche alloys onto your Skoda Fabia, you would have to change the hub from 5x100 cb57.1 to 5x130 cb57.6. So adaptors 5x100 – 5x130 need to be bought. Adaptors range from different sizes starting at 15mm up to custom sizes 100mm+? Before they are bought the offset of the wheels will reduce, so calculations need to be made.

Hub Centric Rings (Spigot rings):

The job of a hub centric ring is to close the gap between your wheel and your hub. For example, Mercedes wheels have a centre bore of 66.6mm. VAG 5x112, as stated earlier, have a hub size of only 57.1. That means, when you sit a Mercedes wheel on new VAG car, there will be a 9.5mm gap between the wheel and the hub on your car. So what you do is get a hub centric ring that has an inner diameter equal to the size of your car (57.1mm) and an outer diameter equal to the size of the hub bore on the wheel (66.6mm in this case). This will close the open gap between the wheel and the hub, thus eliminating any wobble at high speeds. Most aftermarket wheels from say Halfrouds (Halfords) have a larger centre bore so they can be made universal to different makes of cars.

Tire Sizes:

There are three important measurements on the size of a tire, the width of the tire, the height of the sidewall, and the diameter of the wheel. For example, the most common size here is 205/45/16 for 16 inch wheels. This means the width of the tire is 205mm, the height of the sidewall is 45 which is the aspect ration (ratio of height to width), and the diameter of the wheel opening is 16". If you increase the width, lets say to 215mm, you may have to run a different offset to prevent rubbing. If you increase the height of the sidewall, you will get more cushioning, but you might rub your arches. If you decrease, you may get a more jarring ride. The last number can't really be played with, it has to match the size of your wheel.

Changing wheel size, so you go from standard 16†6.5j to 17†7.5j alloys. This means that the width is 1†bigger and the diameter of the wheels is also 1†bigger, so new tires are needed. First of all the 17†alloys need 17†tires, no other size will fit. You have gone up in width of alloys by 1†so the tire will have to go wider, this means fitting 215mm wide tires, or stretching them on the rim (more of this topic later).

When you go up a size in diameter, the profile of the tire will need to come down.

The standard wheel on a Fabia vRS is 205/45/16, so to change the rim diameter to 17†the aspect ratio will change from 45 down to 40, to it will now be 205/40/17.

Stretching tires:

Stretching rubber is safe as long as you're not daft! Most people consider stretching as quite a new trend but in fact, it all began in Japan where they call it 'Hapari'. Drifters used stretched tyres because less sidewall flex was generated, allowing breaking traction easier. Also, because of the reduced sidewall flex a smoother transition from left drift to right drift can be created. So if it is safe to run stretched rubber on a drift car doing over 100 mph on a track then it'll be fine on a modified car. Please keep in mind that you are more likely to break traction so take extra care. Also, remember to up your tyre pressure all round usually by about 6 – 8 psi. Use your common sense and you'll be safe.

Stretch is mainly used so that the tire wall has an angle rather than straight up, which will allow for wider alloys to be fitted under the arch, this is where fitting 205/40/17 tires onto the 17†7.5j rim come into play. Fitting the narrower width of tire will eliminate any chance of scrubbing and catching.

To see what stretch can be achieved follow this link to TYRE STRETCH

Again fitting Porsche alloys to your Fabia means wider alloys, so fitting tires with slight stretch will allow them to fit without scrubbing.

Calculations needed to fit different alloys to your car

Before I fit wheels onto my car I make sure I have all my calculations correct. The following measurements I feel are essential if you plan of fitting wide wheels such as Porsche wheels. All measurement can be done with what ever wheels are on your car at present. Here are the figures you need:

The width of the wheel currently on the car.

The offset of the wheel currently on the car.

The distance from the inside of the wheel to the strut housing.

The distance from the outside edge of the wheel to the arch on the car.

This gives me the figures I need so I know how much space I have to work with.

I then use an offset calculator such as this one here OFFSET CALCULATOR

This compares your current wheel to your new wheel, and you can work out the size of adaptors or spacers needed to get the correct fitment.

Any questions about fitting wheels please put it in here and somebody in the know will help you. Hopefully after reading this you will have a better understanding of fitting wheels. Anything that i've got wrong, or is not clear enough please PM me and i will edit it to clear it up.

Cheers Phil

Edited 27 August, 201015 yr by pip_vrs

Awesome post

Really informative and should defo be made a sticky

cheers

Awesome post

Really informative and should defo be made a sticky

cheers

Thanks mate, wasn't sure if it was needed or not though. I've had a loa of people PM me about fitting wheels so thought if i could put the info in one place it will be easier. I dont mind people PM'in me by the way haha

How do i decide what colour to refurb them in??

And what tyres should i put on them??

Seriously though top work pip - couldn't really ask for more but i have a feeling it wont stop the "will these fit" threads

One suggestion might be a "these will bolt straight on" list ie Octavia mk1, Fabia Mk2, Leon Mk1, VW Golf Mk4 etc etc

Edited 27 August, 201015 yr by PastyBoy

Should now be sticky...

Should now be sticky...

Thanks alot.

As to what colour to refurb them.. do them pink

Another issue is wheel bolt types. VW use radius seat bolts and aftermarket wheels often use taper seated wheel bolts. Bear in mind that an aftermarket alloy wheel could be thicker or thinner for the section where the wheel bolt shaft goes through. Meaning a different shaft length of wheel bolt required.

Pretty sure I have a spare set of tapered wheel bolts of standard length if you need the Jason, if they are tapers seats dont use the radius bolts, they wont tighten up correctly.

I have a set of seat leon alloys (mk 1) they ave an offset of 42 and are 7jx16h2

Will i need to get a set of 10-15mm spacers for these?

I know they will sit in a bit but as they are 7j rather than standard 6.5 im thinking they may not need spacers?

Im currently on my iphone so not easy to do it for you, but if you put the standard wheel speck into the 'offset cslculator' link in my first post and your new wheels it will calcilate how much the wheels will move over standard. If you get stuck drop me a pm.

This post saved me asking some daft questions. Thanks.

I love it when I go from ignorant to informed...... great post, sticky for me

Thats what its here for mate :-)

Hi can i put on mi Fabia 1.9 TDi estate 51 reg. alloy wheels from audi A4 205-55-16"

And will i pass MOT later on with it?

Great post. Thank you!!

hi guys, got a problem with fitting wheels, recently got some 16' 5 spokes from an audi, there 205/55/r16 tyres now all of them fit fine except the rear left side which rubs against like a triangular shaped part of the shell on the rear of the arch, any ideas guys?

Rob, the profile is too big on the tyres. It probably ought to be 45 rather than 55, hence the rubbing.

Will I be able to put Fabia Mk.1 RS 16" stock alloys on my 2010. Fabia 1.2TSI?

My wheels are 15"x6 ET43. And the RS ones are 16x6.5, ET42 or 32? Cant find the exact info anywhere. :|

Will I be able to put Fabia Mk.1 RS 16" stock alloys on my 2010. Fabia 1.2TSI?

My wheels are 15"x6 ET43. And the RS ones are 16x6.5, ET42 or 32? Cant find the exact info anywhere. :|

Yes they will fit. No problems.

Thanks! :beer:

Can't believe some one has voted that this is RUBBISH!

I appreciate the effort that's gone into this

Thanks op

Will 17 inch fit on my fabia that has 14 inch?

Will 17 inch fit on my fabia that has 14 inch?

Yes with 205/40 17 tyres they will have the same rolling radius as your 14" wheels + tyres

Thankyou, I will be looking for some alloys then

Will 17 inch fit on my fabia that has 14 inch?

Yes with 205/40 17 tyres they will have the same rolling radius as your 14" wheels + tyres

Thankyou, I will be looking for some alloys then

Just checked + the rolling radius would actually be slightly bigger but if u follow this link below it will barely make any difference to the speedo reading.. but they will def fit.. all mk1 fabias are the same regardless of what wheels it came with from the factory

http://www.willtheyfit.com/index.php?width=185&aspect=60&diameter=14&wheelwidth=6&offset=38&width2=205&aspect2=40&diameter2=17&wheelwidth2=7.5&offset2=35&Submit=Submit