Want the best wheel and wheel fitment tips, hints and tricks? Well look no further than our wheels FAQ.

Here at FC we’re often asked technical stuff via the mediums of email, Facebook and being shouted at in the local Maccie Ds. Now, obviously we are pretty amazing but, contrary to popular belief, we don’t know absolutely everything about everything. Luckily though we happen to have a team of industry experts on hand to deal with the really tricky stuff. This month we catch up with Mark Ewington, bossman at Cades Wheels to answer all your questions about wheels and wheel fitment.

WHEELS WHEEL FITMENT TIPS TRICKS ADVICE

How do you go about designing a new wheel?
Well, unlike what most people imagine, it doesn’t come out of thin air, it’s actually pretty involved. Every wheel company is different in their approach but, speaking for us, we like to look at market trends in terms of style and sizing and then sketch some freehand ideas. When we get one we like it has to be professionally rendered and drawn in 3D for the factory. In the case of cast wheels, like standard wheels and the vast majority of aftermarket wheels, only then can we start making prototypes, moulds and final versions. It’s not a cheap process and that’s the reason most wheels come in a limited number of widths and diameters. It’s important to get the process right as it’s very difficult to change the mould once it’s been made!

I’ve been told I need to fit coilovers for my wheels. Why?
Coilovers have slimmer springs and cups than standard suspension so it’s probably because you need the clearance inside the arches for the extra girth. Then again it could be that the offset of the wheels is a little too high. Offset is one of the most important factors in getting your fitment spot on – it’s basically how far your wheels sit in the arches. High offset wheels that are too far in could foul on the suspension or steering components, low offset wheels that are too far out can foul on the arches. Any rubbing at all is an instant MoT failure, not to mention bloody dangerous.

WHEELS WHEEL FITMENT TIPS TRICKS ADVICE

What does ET38 mean?
That’s how we express the offset of a wheel. The ET comes from the German word ‘Einpresstiefe’ which means ‘insertion depth’ and the number is the distance in mm from the centre line of the wheel. In the case of ET38, which is a positive offset (as opposed to ET-38), it means the mounting surface of the wheel is 38mm closer to the front of the wheel then the centre line. This will sit 38mm deeper into the arch than a wheel that’s ET0.

They say I shouldn’t do up my wheels with a big bar, why is that?
It’s tempting I know, because obviously you don’t want them coming off, but tighter isn’t always better because at the very least over torquing will damage the bolt holes on the wheels. The worst case scenario will be stripped threads on your studs or in the bolt holes making the wheels even more likely to fly off. Always use a torque wrench to the manufacturers’ standard spec and, even more importantly, avoid banging them on with a big powerful impact gun.

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How come some wheels cost hundreds and some wheels the same size cost thousands?
There can be a number of reasons, but the most simple answer is that some manufacturing processes are more expensive. In the case of forged or multi-piece wheels there’s a lot of work and materials involved to get a finished product. That, coupled with the fact that they’re generally rarer than cast wheels, plus usually made to order and mostly finished with custom paint, chrome or anodizing, pushes the price up significantly too. Off-the-shelf cast wheels are generally less expensive because they’re made in huge batches and all finished ready to go.

Can I fit my standard tyres to a new set of wheels?
If you’re fitting bigger or massively wider wheels then they won’t fit but, as long as the new wheels are the same diameter and a very similar width, there’s no reason why you can’t. If your tyres are brand new I can see why you’d want to, but bear in mind most dealers offer wheel and tyre packages that can be a lot more economical if you’ll be needing to replace the tyres anytime soon. These guys will usually buy perfectly matched tyres in bulk and have them ready fitted to the wheels – all you need do is bolt them on. There are some parameters you will need to stick to, you need to marry your tyre size up to the size and width of your new wheels – you can find technical information by ringing us here at Cades Wheels.

Why do bigger cars have more studs/bolt holes than smaller cars?
It’s a safety thing, a bit like how a 16-wheel artic has 10 or 12 lug holes. For heavier or more powerful cars, usually the number of studs increases – it’s a simple case of spreading the load over more studs or bolts.

Is a wider PCD, like Porsche’s 5×130, better for performance?
As for how fast your car goes or how well it handles? No, it makes no difference at all.

My Punto is 4×98 but no one makes wheels I like in that PCD, any ideas?
True, 4×98 wheels are rare, but in most cases you’ll be able to fi t 4x100PCD wheels with vari-bolts. Sometimes affectionately known as ‘wobble bolts,’ these have a movable seat that locks the wheel in position as you tighten them up. With these you can usually get away with one or two millimetres difference in the PCD.

My girlfriend says bigger is better when it comes to wheels, is that true?
It depends if you’re driving a monster truck or a Corsa. While it’s true most people like to add an inch or two in diameter, and that always looks cool, squeezing 22s on a car that came with 15s as standard is pushing it somewhat.

My new wheels come with some plastic rings in a fitting kit, what are they for?
Spigot rings are found on most aftermarket wheels, so one wheel fitment can be used on numerous applications. Rings are used to reduce the centrebore on the wheel to the correct hub size on the car and to reduce any vibrations.

I have a set of wheels that are ET40 offset but have been told my car needs ET35, what can I do?
The simplest way would be to get yourself a 5mm spacer to push the wheel 5mm out and bring the offset down to where it needs to be. TPi Spacers start at 3mm.

WHEELS WHEEL FITMENT TIPS TRICKS ADVICE

Apparently I need to use radius nuts with my wheels, what are they?
It’s really important to match the wheel nut/bolt seat to the wheel otherwise they won’t tighten properly, could damage the bolt holes and will most certainly be dangerous. There’s various types of nut/bolt seat, the most common being tapered but the one you want though has a rounded seat. You’ll find most new wheels will come with a fitting kit containing the correct nuts or bolts – have another look in the boxes. It’s always worth checking… and remember, all our wheels come with a specific fitting kit.

WHEELS WHEEL FITMENT TIPS TRICKS ADVICE

I have a set of wheels that are ET40 offset but have been told my car needs ET35, what can I do?
The simplest way would be to get yourself a 5mm spacer to push the wheel 5mm out and bring the offset down to where it needs to be. TPi Spacers start at 3mm.

My new wheels come with some plastic rings in a fitting kit, what are they for?
Spigot rings are found on most aftermarket wheels, so one wheel fitment can be used on numerous applications. Rings are used to reduce the centrebore on the wheel to the correct hub size on the car and to reduce any vibrations.

Can I run staggered wheels on my 4WD car?
It’s not really a good idea because it can play havoc with the drivetrain. With 4 wheels the same width, with the same tyres, each will be the same overall diameter. This means they all make the same number of revolutions over any given distance, turning the differentials and drive shafts as they go. As soon as you start fitting wider tyres with different profiles or stretching rear tyres it changes the diameter and the number of revolutions on the front and rear axles won’t match. That’s not to say it can never be done within the car’s tolerances, but it takes some serious working out of tyre sizes and wheel diameters not to cause any damage.

Why do some cars come with wider wheels on the rear as standard?
With powerful rear-wheel drive cars, many manufacturers will fit wider rear wheels so they can fi t wider tyres with more grip. These cars are normally pretty tail-happy to begin with, so the idea is to promote a degree of understeer which is much easier to deal with for your average driver than loads of oversteer.

WHEELS WHEEL FITMENT TIPS TRICKS ADVICE

My Dad says he used to have magnesium wheels? Is he yanking my chain?
I don’t know your Dad but it’s entirely possible. Some of the first lightweight racing wheels were made of magnesium and ‘mag’ wheels became popular on road cars in the ’60s. The trouble with magnesium though is it rapidly breaks down when exposed to moisture and is always susceptible to pitting and corrosion. They’re also pretty much impossible to put out if they catch fi re from a burning tyre or scraping on the road because magnesium can burn under water and CO2. For that reason they don’t make them anymore and wheels are now cast in aluminium alloy. So yeah, he could have had a set sometime in the past, I’d still love a set myself.