Recommended size tyres for 17 inch wheels

Smudgemanuk

Smudgemanuk

Zorg Guru (II)
British Zeds
Joined
Dec 1, 2024
Points
104
Location
Bicester, Oxford
Model of Z
2.8l TU pre-facelift z3
As said above...

I am looking to buy some 17 inch wheels, and would like to cost up some tyres for it, hence I need to know the sizes

Thanks
Chris
 
Go to

www.willtheyfit.com

There you can key in your current size wheel/tyre and then your desired sizes and it'll tell you whether the rolling radius is the same. Speedo error etc. Also play with offsets to see if wider will stick in/out more etc
 
As above willtheyfit is very useful.

It depends on the wheel widths and if they are staggered (ie wider rears). I know the 'standard' tyre sizes for 17" staggered style 18s are 225/45 front and 245/40 rears. The rears have a smaller aspect ratio, as the tyres are wider because the aspect ratio is a percentage of the width.

As a general rule for the same width of tyre, if you go up and inch in diameter you go down one increment (5%) in aspect ratio.

You should keep the rolling radius (circumference) of the tyres to within 5% of the factory spec, or it can cause problems with the ASC/ DSC. Also, your speedo will not read anywhere near correct.

Just remember OP, as I know you are a (very) youngster; your insurance company will want to know if you change wheels, as it is a 'modification'.
 
Thank you both for your help

I will take a look at willtheyfit, thanks @Duncodin

@Pond - That general rule is new to me—appreciate you sharing it
And thanks for the heads up on the insurance, I have already checked about declaring it, and luckily the change is negligible. They do kick up a bit of a stink if you fit aftermarket ones tho.

Much appreciated from you both

Chris.
 
I would recommend the 17inch staggered set up. The good thing is that it was available from new so it’s not a modification. If you put your reg in the search on Kwik Fit for instance it will show you all the options.
IMG_3216.webp


A popular modification is to add wheel spacers, particularly on the rear. Without spacers, the rear can look a bit silly, particularly with the narrower wheels. Anything from 10 to 20mm spacers seem to improve the look.

Below of a stock z3 with 16 inch wheels and probably 205’s all round and mine with staggered 17 inch wheels with 3mm spacers at the front and 15mm spacers at the back. My car had those spacers on when I bought it. Seemed a bit random to me, but I like the look so I kept them on.

IMG_5651.webp
IMG_7044.webp
 
Thanks for the Kwik Fit idea

I have considered adding wheel spacers, but I was worried it would negatively affect the handling, but I am not sure really

They definitely improve the look though!!

Chris.
 
It will positively affect handling only.

Tony.
 
Smudgemanuk said:
Thanks for the Kwik Fit idea

I have considered adding wheel spacers, but I was worried it would negatively affect the handling, but I am not sure really

They definitely improve the look though!!

Chris.
Click to expand...
Just be VERY careful with spacers and insurance. Insurance companies DO NOT like wheel spacers, for good reason.

Spacers increase the track of the vehicle, so effectively making the wheel hubs wider. This means that the weight borne by the wheels, which is the full weight of the car, is further out than it was designed to be, so putting exponentially more stress on the suspension linkages and pivot points.

I know that thousands of people use spacers and the common response is "I've used spacers for 30 years and never had a problem", but the physics don't lie. They are detrimental to suspension and, by association, handling.
 
@Pond

I was just reading up on suspension stresses through wheel spacers! That's a good thing to be aware of, thanks

Affecting insurance is definitely a good point, I shall do a test and see how much is raises it!

I am only in the first stages of considering spacers so I shall have a good think about it

Thanks Chris.
 
I run 17s and have 245/45 17 all round, on pilot sport 4s and they stick like glue!
 
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My 3.0 has BMW 17’s from the factory
It runs some real cheap ‘roadcruza’ brand I found. ‘SNC tyres from china’
I think they are good and really surprise me how well then run.
Bearing in mind too, the front and the rear run different sizes.
They are about £65 a tyre - BUT - I don’t run them in them in the wet or the winter.
 
JonnyBravo said:
My 3.0 has BMW 17’s from the factory
It runs some real cheap ‘roadcruza’ brand I found. ‘SNC tyres from china’
I think they are good and really surprise me how well then run.
Bearing in mind too, the front and the rear run different sizes.
They are about £65 a tyre - BUT - I don’t run them in them in the wet or the winter.
Click to expand...
My Z3 has 16" wheels, 225/45-R16 tires.The tires are from China, low cost $60 each, and I was going to hit up my grandson, who works at a tire chain in Ft. Worth, for some better tires with his discount. ( Those tires aren't the only thing cheap ;) ) I looked the tires up on google, and found they're actually pretty good tires, and so far they've been pretty good in all kinds of weather.
 
Guinn said:
My Z3 has 16" wheels, 225/45-R16 tires.The tires are from China, low cost $60 each, and I was going to hit up my grandson, who works at a tire chain in Ft. Worth, for some better tires with his discount. ( Those tires aren't the only thing cheap ;) ) I looked the tires up on google, and found they're actually pretty good tires, and so far they've been pretty good in all kinds of weather.
Click to expand...
Honestly you won't regret pilot sports 4s. Make sure you get the s version. Extra sticky 😉 i wouldn't have them on a daily though
 
t-tony said:
It will positively affect handling only.

Tony.
Click to expand...

Pond said:
Can you please explain how?
Click to expand...

I imagine it can improve handling by widening the track. The center of gravity is different. Car leans different.

But there's no such thing as a free lunch.

That improved handling puts more strain on the components. If you're in a race team you accept the strain and go wide and replace components every race. Road cars want to get a lot of miles out of standard fit.

As for the increased cost of insurance. This likely isn't an issue with safety. But insurer's statistics likely show that the kind of person who fits spacers is the kind of person who wants to go round corners quicker. But the same could be said for those ford focus drivers who fit dustbin sized tailpipes. In fact any modification even if it doesn't improve performance is a red flag to insurers.
 
Depends if you are just bimbling or hooning.

Bimbling go cheap
Hooning Pilots Sport 4s or 5s :thumbsup:
 
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