Just got some 16" wheels, think they have the wrong tyr

[adam81]

Just got some pretty nice dishy alloys (apparently BMW, don't know what they're from- will post pics eventually), 16s, bought them on ebay from a guy who was apparently going to put them on an e30. They tyres are 215 40s, they're brand new eagle F1s! Got the wheels and tyres for 200 quid, which is a bit good really considering the tyres. BUT! These tyres are too small right? They're certainly smaller than the ones on the original steels that came off the car. And I'm pretty sure 70 doesn't feel as fast as it used to... anyone?

[josh-hocking]

post the ebay link!!

[adam81]

Ah hah, good idea. They stay open for a while after buying don't they? I've had them for a couple of weeks.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :IT&ih=010

[jaffro]

there quite nice i like them

[march109]

The wheels are 16" and the profile is 40, so its probably not far off the same rolling radius as 15" wheels with 55 profile tyres, but frankly I can't be bothered to work it out because I know they will be as close as damn near the same. Think about it, your old wheels were smaller but had a taller tyre wall, your new wheels are 1 inch larger and the tyres are 15mm smaller tyre wall!

And as for 70 doesn't feel like 70 anymore, in what sence? if its less crashy and noisy then thats a good thing surely. One other thing to note that because 15mm (does not) =/= 1inch = 25mm (ish) your speedo will be slightly out but not by much at all, some zoners are running 17inch and 19inch wheels before tyres are considered with no major issues with speedos.

[StuBeeDoo]

I've done a quick calculation and I work it out that 205/50x16 is nearer to 205/55x15 than your 215/40's. The 215's aren't that far off though.
I can't see that it would make much difference to the speed of the car, there's not enough variation for that.
HTH
Stuart

[Jeepster]

this may help

http://www.miata.net/garage/tirecalc.html

[adam81]

"Think about it, your old wheels were smaller but had a taller tyre wall, your new wheels are 1 inch larger and the tyres are 15mm smaller tyre wall!"

Umm, I'm confused, I thought the '40' number was not mm, but a percentage of the width of the tyre?

Thanks guys, tyre sizes annoy me. Overall the new wheels are definitely smaller than the old ones though. We'll see. I've had a 525 for the last year, maybe it's just destroyed my perception of speed altogether.

[AlpineAde]

Think of it in these terms, then. A smaller rolling diameter changes your gearing. You've just given yourself quicker gearing.

[gIzzE]

Yeah the 40 is a percentage of the width, so it is 40% of 215mm.


You will be over reading speed wise, so better than under reading from a legal point of view, when your speedo is reading 60mph you will be travelling at a smidge over 57mph.
Not too bad, but the E30 is already about 5mph out using the stock tyre size, so when you are reading 60mph you will probably be travelling around 52/53mph using your new tyres.

You can verify this with a sat nav unit.

My main worry with this is your mileometer will also be out, as will any mpg calculations, so for every 10k miles you do in the car, the mileometer will say you have done 12k miles.
Get to 100,000 and it will say 120,000, get to 150k and it will say 180k.


I would put 205/55/16's on, this would make the speedo pretty much spot on and makes it very comfy too. Or 215/50/16's on it it, this is pretty much the same as stock 14's and 15's with a little more grip, at the expense of slightly higher consumption because of the higher rolling resistance.

I lost 5mpg on my 320d going from 205 wide stock tyres to 265 wide tyres.

[gareth]

i've been running 215/40/16's for a while and think they're great. you'll not get that stretched look with a taller tyre. as for gearing, it works out about the same as dropping to the next lower diff ratio

[BMJG]

on 16's i always run 205/45/16 tyre works out just about right and always keep a load of spare ones also as sometimes can be a pain to get hold of

[capri_rob]

Somebody was looking for a set just like those on here a few days ago but can't find the thread now......

I think it was established that they were made by 100+ .... I seem to remember them being very popular in the mid '90's although to be fair that's a much deeper dish wheel than most of the ones you used to see about.

Get some pics up with em on the car

[Jhonno]

I would put 205/55/16's on, this would make the speedo pretty much spot on and makes it very comfy too. Or 215/50/16's on it it, this is pretty much the same as stock 14's and 15's

Both of those are too big..

Even 205/50/16 is slightly bigger than a 205/55/15

[adam81]

Thanks for all the replies gents. I can't understand why one of the tyre measurements they put on the side isn't the overall diameter, but hey. Well that's going to make my MPG calculations all the more difficult isn't it. Bah, will have to find something else to do on a saturday evening. So the the e30 clocks are out by 5mph anyways? Up or down?

[adam81]

And hey jeepster, thanks for that link, that little application answers a lot of questions, nice one.

[tailoutcharlie]

215/40/16 will be exactly 29mm smaller than 205/55/15 which is quite a lot smaller so will alter yous speedo. be careful going thru speed cameras etc.

id leave em on till you wear out the tyres as they're damn good tyres. may look a bit odd tho

hth

[gIzzE]

I would put 205/55/16's on, this would make the speedo pretty much spot on and makes it very comfy too. Or 215/50/16's on it it, this is pretty much the same as stock 14's and 15's

Both of those are too big..

Even 205/50/16 is slightly bigger than a 205/55/15

I know, but they fill the arches better and even out the 5-8% over read that is built into the E30.

[gareth]

regarding what they look like, the pics in my sig is with 215/40/16's on, with a heavy drop

[StuBeeDoo]

So the the e30 clocks are out by 5mph anyways? Up or down?

Mine over-reads by 5mph up to 70, then 3mph to 80 (compared to my GPS).

[zaust]

Coincidence. I just bought a set of these for track use in 15's.

Any way. Should be a 45 profile. And like fuzzy I run 225/40/16 on a big drop.