I thought I knew about wheel sizes.
Discussion
I bought an E90 BMW 320d Efficient Dynamics last year, having driven it from new for two years as a company car. I decided I liked it enough to buy it from the company at the end of that period, at the price they offered it at. As a consequence, it's now my car so it's gone from "basic maintenance" to "is looked after properly".
One of the reasons I like it is that it wears factory-fitted tyres (Michelin Energy Saver +) with a sensible profile (205/55/R16) on its 16" wheels. They last quite a long time (the car has done 43K miles and is only just on its second set). It makes hitting potholes less of an issue for me, and my opinion is that the primary ride quality is very good compared to the popular "big wheels, low profile tyre" setups on these cars. It even handles pretty well on real (bumpy) roads compared to stiff M-sport type suspension setups. I digress.
One small downside to the car is that I need it for work, and I won't always be able to look out the window and say "no, looks like it might snow or be awful to drive in, not happy about travelling in that". Sometimes I'm going to find myself in poor driving conditions, hundreds of miles from home (I've several years of experience with this, and it has happened to me several times with other cars). I have snowsocks for the BMW that travel in the boot in winter, but they are rather limiting in speed and range.
As a consequence, I decided I'd like a set of spare wheels and I'd put cold weather tyres on them. To make insurance declaration redundant, I decided I'd like the same size and model of wheel as are currently on the car: BMW Style 306, 16". (Side note: 17" versions of the same wheel style are available as a fitment to the X3, but they aren't standard fit on the E90 3er).
So I'd been looking for a secondhand set of 16" wheels for a while. The prices of a new set are quite high (£900!) compared to what I wanted to pay. Last week I found a complete secondhand set for £162 including delivery and went for it. They arrived by courier this morning.
I took a tape measure with me to the courier's van to check the rim sizes and nearly rejected the delivery on the spot because to my horror they were 17". I decided to actually accept them and talk to the vendor about it, and I'm glad I did that.
[These photos taken a short while later]
Here's the 17" wheel.
On the back of the wheels, most confusingly, I found the following mark, showing "7Jx16" (7J wide, 16" tyre)
I then took the step of measuring the same face on one of the 16" wheels currently fitted on my car.
Guess what - my 16" wheels are 17" across the front face!
So after a small amount of internet digging, it turns out that 16" really refers to a 16" diameter mounting (bead) for the tyres, rather than the actual wheel diameter. Feel free to laugh at the idiocy etc. I hope someone finds this helpful.
Craig (more humble than usual)
One of the reasons I like it is that it wears factory-fitted tyres (Michelin Energy Saver +) with a sensible profile (205/55/R16) on its 16" wheels. They last quite a long time (the car has done 43K miles and is only just on its second set). It makes hitting potholes less of an issue for me, and my opinion is that the primary ride quality is very good compared to the popular "big wheels, low profile tyre" setups on these cars. It even handles pretty well on real (bumpy) roads compared to stiff M-sport type suspension setups. I digress.
One small downside to the car is that I need it for work, and I won't always be able to look out the window and say "no, looks like it might snow or be awful to drive in, not happy about travelling in that". Sometimes I'm going to find myself in poor driving conditions, hundreds of miles from home (I've several years of experience with this, and it has happened to me several times with other cars). I have snowsocks for the BMW that travel in the boot in winter, but they are rather limiting in speed and range.
As a consequence, I decided I'd like a set of spare wheels and I'd put cold weather tyres on them. To make insurance declaration redundant, I decided I'd like the same size and model of wheel as are currently on the car: BMW Style 306, 16". (Side note: 17" versions of the same wheel style are available as a fitment to the X3, but they aren't standard fit on the E90 3er).
So I'd been looking for a secondhand set of 16" wheels for a while. The prices of a new set are quite high (£900!) compared to what I wanted to pay. Last week I found a complete secondhand set for £162 including delivery and went for it. They arrived by courier this morning.
I took a tape measure with me to the courier's van to check the rim sizes and nearly rejected the delivery on the spot because to my horror they were 17". I decided to actually accept them and talk to the vendor about it, and I'm glad I did that.
[These photos taken a short while later]
Here's the 17" wheel.
On the back of the wheels, most confusingly, I found the following mark, showing "7Jx16" (7J wide, 16" tyre)
I then took the step of measuring the same face on one of the 16" wheels currently fitted on my car.
Guess what - my 16" wheels are 17" across the front face!
So after a small amount of internet digging, it turns out that 16" really refers to a 16" diameter mounting (bead) for the tyres, rather than the actual wheel diameter. Feel free to laugh at the idiocy etc. I hope someone finds this helpful.
Craig (more humble than usual)
I knew that.
It's worse though when a person balancing your wheels doesn't know that, measures the wheel with the wee calipers edge-to-edge and then sticks those numbers into the machine before spinning it up. Machine suggests weights fitted according to the data he's entered and then he wonders when checking the balance (asuming he bothers his arse to check) why the machine asks for a counterbalance, or he doesn't wonder at all and just sticks them on like the incompetent dick he is.
It's worse though when a person balancing your wheels doesn't know that, measures the wheel with the wee calipers edge-to-edge and then sticks those numbers into the machine before spinning it up. Machine suggests weights fitted according to the data he's entered and then he wonders when checking the balance (asuming he bothers his arse to check) why the machine asks for a counterbalance, or he doesn't wonder at all and just sticks them on like the incompetent dick he is.
CraigyMc said:
showing "7Jx16" (7J wide, 16" tyre)
Another little nugget (apologies if you already know this), the 'J' doesn't refer to the width in any way (so the wheels aren't 7J wide, they are 7" wide); the J is referring to the shape of the bead. J wheels need to be fitted with J-bead tyres, JJ wheels need to be fitted with JJ-bead tyres, same for K, etc. (I can't remember any of the other designations).xRIEx said:
CraigyMc said:
showing "7Jx16" (7J wide, 16" tyre)
Another little nugget (apologies if you already know this), the 'J' doesn't refer to the width in any way (so the wheels aren't 7J wide, they are 7" wide); the J is referring to the shape of the bead. J wheels need to be fitted with J-bead tyres, JJ wheels need to be fitted with JJ-bead tyres, same for K, etc. (I can't remember any of the other designations).
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