15" vs 17"

[oze30]

Right. I have the choice of either 15's or 17's. !7's look wicked, but cost more than the 15's. 15's are nice, but need tyres (17's already with tyres)

Its for a 325 touring. Will the auto handle the 17's-or will it crap itself? What about speedo and revs?

(it has 15"bbs atm)

[JOSEMI]

My favourite wheels are 15" BBS and Alpinas, unless the 17" are Alpinas then leave the BBS.

Jose

[Cotty]

My favourite wheels are 15" BBS and Alpinas, unless the 17" are Alpinas then leave the BBS.

Jose

I though original Alpina's were 16" and the fakes are 17"

[Hyperion]

if u are running 15' at the moment and u are happy with the look why change to another set of 15's. 17 look cool and there are a lot of cars on the site with 17's. But saying that , depending on how wide the 17's are , and if you have a lowered car ,you could get rubbing on the archs. 325i has more than enough power to shift 17"s.
i am personaly looking for a cool set of 16"s , i am running 14" at the moment.
Cotty: the original alp's were 16"

[orangecurry]

there are two questions here... no three questions

1) what about speedo and revs? - what is important is that the rolling diameter of the wheel is correct - thus a 205/55/15 has about the same diameter as a 205/45/17 (606mm vs 616mm), though 215/40/17 at 604mm is even closer (but might be too wide)

so get the right tyres whatever else you decide

2) 15" wheels will handle infinately better on normal roads over 17"; 16" is ok, but 17" is a bridge too far; 15" BMW BBS are also one of the lightest and strongest wheels available - when you run over a pothole in your 17s, be sure to have saved up enough money for a new rim or new tyre

3) which looks better? ahh that'll be down to you

[oze30]

Looks.. i already know which, They're both the same styl-ish.. mim and supertourismos. Main prob is, need to sort out the leaks I got.. and new brakes allround!!

[orangecurry]

leaks?

[Stoney_god]

I run 17's on mine.. 215/40/17 front and 225/45/17 rears. Looks good, handles fine.

[Jhonno]

i run 16 BBS' on mine and i find the handling is awesome.. ok im running better suspension than when i was on 15 BBS' but i cant see how extra tyre wall will help..

[Andy_magic]

For wheel fitments I use a basic guide:

For every inch you increase you drop a profile.

IE Standard is 205/55/15 if you went to 16's you should fit 205/50/16, for 17's 205/45/17 etc.

I have no experience of larger wheels on an E30 but everything else I've had with larger wheels by 2" have all tramlined like hell.

Personally I'd rather have 15"s with some exotic rubber than 17"s with average rubber, but it is a matter of personal taste, there is no right or wrong, apart from TSW Venoms = pure wrongness

[JOSEMI]

Cotty 180: I said

unless the 17" are Alpinas then leave the BBS

I don't know if there is a version of 17" Alpinas or not, I said that unless the Alpinas are 17", then I would leave the BBS on the car.

sorry mate not been caught yet.

(wouldn't it be nice to help oze30 instead, specially knowing that he joined recently and wants our opinion ??)

Jose

[Moofles]

17" alpinas exist in 5 stud and might fit onto a 5-stud converted car, or m3...

loads of people run 17s too, with a 40mm drop or less you are ok, and the standard tyre size is 215/40/17 which won't rub...

[orangecurry]

I am trying to help - I'm warning him about the differences that 17s will bring.

I didn't say 17s were crap or dangerous or anything. I have run 17s on a RWD car... 245/40/17 to be exact

what I said was
'15" wheels will handle infinately better on normal roads over 17"; 16" is ok, but 17" is a bridge too far;'

This is not just my opinion; this is well known. For a given rolling diameter the increase in sidewall makes a large difference. The smaller the sidewall, the less flex; a larger sidewall also contributes to the effect of suspension; these two things together mean than for any normal (bumpy surface) road, a larger profile tyre will
a) have more surface area in contact with the road as it deforms more
b) as it flexes more it will allow lateral movement rather than slipping sideways.

Hence a bigger profile will warn the driver that you are on the edge of traction, and in any case this limit will be reached later.

As someone above has said, spend the money on the tyres - you really DO get what you pay for.

[E30BeemerLad]

can't support what Orangecurry has said enough here, if I was keeping my shed then I would eventually be putting some 15" Mim 1900's on, got the Alpina reps on as you can see in the sig pic, they look good but you pay for it with loss of ride quality with rubber band 40 profile tyres.

So you get a crashy ride as there is not as much absorbance and also you get less of a warning when you are getting near the limits of adhesion as there is less sidewall flex.

Just depends on what you want mate. Looks but less supple ride and having to pay Ԛ£70+ a tyre if you want something with some traction or stick with 15's where the handling and ride will be much improved. Just avoid Nankangs, they are utter rubbish, could not believe the difference some Uniroyal Rainsports made to the rear of my car.

[Moofles]

lol, i wasn't arguing with you - in fact i would go for the 15s probably, cos tyres are important (if its a toss-up between good and bad tyres).

However, i do disagree with your statement about 17s being a bridge to far that is just your opinion - but also the opinion of many other people. Actually, it just depends a lot on what roads you drive on - on relatively smooth roads (an urban myth in this country) the 17s will be superior to the 15s...

Actually 17s can have slightly better steering response too (don't know if it's noticeable though) because you have less tyre flex when you make a steering adjustment...

oh, also one point (and this really irritates me so forgive me if i sound annoyed!) - for a certain psi, a tyre in 15 and 17 will both have the *same* contact patch - it's physics, all you get is a change in contact patch shape. All to do with the weight of air, and the pressure, and something or other...i'll need to whip out me physics book to give the full, proper answer though (which i cba to do unless someone really moans )

[orangecurry]

when I said I was trying to help, I hadn't even seen Moofles post (it took me so long to write mine!) so a bit of confusion there? Anyway...

Physics? Quoting 'physics' at someone is a bit like Foghorn Leghorn saying 'you can argue with me son, but you can't argue with Mathematics...'

you may be right.... or not

can we all agree that 17s will have a harsher ride and dump you into the scenery sooner on a rainy day?

[Moofles]

haha, oh i didn't realise - never mind eh

not quite sure what you mean about the physics thing though, lol - it *is* right - here's an attempt at demonstrating something that might help:

http://www.sheldonbrown.com/tyres.html

Scroll down to 'Width and Pressure'

Although it's talking about bicycle tyres, this also applies to car tyres (in fact, it applies more generally than that - just to pressure and load). The two factors that are involved are load...and pressure

load (weight on the tyres - the car) is the same. And if the pressure is the same, the resulting contact patch is the same.

That's why if people put wider tyres on a car to get more grip, it's b*llocks - you need to lower the pressure. Actually that leads me to the statement

"If you are comparing two tyres of similar construction, with the same load, and the same pressure, either the wider tyre is overinflated, or the narrower tyre is underinflated!"

in the above link - I mention this cos usually you get some smartarse telling you how they measured their contact patch and its bigger, etc, etc - well normally a 17" will use different pressures to a 15". Also, the material used will matter (how easily it deforms).

But to answer your last question yes i can agree that on britain's roads, 17s will give you a harsher ride - and will deform less before losing grip (which may or may not mean you crash sooner - if the grip is the same, then it relies on the driver being able to spot - or "feel" - the deformation occurring sooner on a high profile tyre. The point at which the tyre loses grip I think will be the same...)

[Dan318-is]

in my opinion it doesnt matter what size tyre or wheel you use on british road, the ride is still guna be shit becuase the tax we pay goes towards fucking speed traps and to pay fuckers to sit there with lazer guna rather than actually helping to improve the tarmac we drive on

[oze30]

Hmm.. interesting debate! Should have made this a poll eh??

Sidewall deformation.. on a car tyre I think is negligable unless your drifting or racing, hence the lower profile tyres for racing. 15's ride better, 17's handle better... TO A DEGREE. i agree with all the arguments, but to me, some are wrong.. or rather less correct.

Just trying to sort out what's what, and whether it would be beneficial to upgrade to 17's over 15's. Cost is a big factor, so i can see 15's winning on that point. HOWEVER, handling ( AND I know that the E30 doesn't handle THAT well) is also important. I think 16's would be a good compromise, but trying to find a set is not fun!

[Dan318-is]

Everyone would love 16s

tyres are also the most expensive for 16s though

[Simon13]

the speedo will be fine as the reading is taken from the diff. It's only if u use 19's or something where the wheel is way larger than the overall diametre of a 15bbs with 55 profile

We have had a million arguments over which size is best!

[Hyperion]

i am having a problem finding 16" over here aswell, i go into a shop:
Me: "hi, can you sell me a set of 16" wheels?"
(guy looks at me like i have mad cow syndrome)
Guy: "ahh, you know 16 will cost as much as 17's"
Me: "i know, but i am going for a certain look and size of tyre"
Guy: " sure no problem, we have 14,15,17,18,19,20"
Me: "no i want 16's"
Guy: "ahh....you sure?"

[Simon13]

no one does 16's! pain isn't it. Only 16's that look good and are not made of monkey metal are alpina/hartge wheels. Finding them is the trouble. Then there are schnitzer/racing dynamic 16's aswell but they are virtually non existant!

oh the joys of finding nice 16's are a head ache for sure

[E30BeemerLad]

Quality sig pic Kermit

[oze30]

Funny how 16's are rare over here. back home 16's are more popular. Heaps of 15/6/7/8 and now there's more on 20+. try this site!


www.tempetyres.com.au

it's an australian site.. but it will show you the choice of wheels we get.

Remember, the conversion rate is.... 2.50AUD = 1 GBP!!!!

damn those conversion rates!!

[fuzzy]

depends what you are after, if your after a car that handles better with lower suspension then id go for the 17 with a lower 40 profile tyre, theres less flex it the tyre sidewall so itll feel sharper, but the downside is the ride will feel a lot harsher and bumpier. i think it for every inch over standard diameter drop a profile on the sidewall which keeps the rolling diameter roughly the same....17's all the way for me...i wanted 18's but couldnt get alpinas

[Simon13]

thing is the smaller the sidewall the less flex u get and then the back goes, hedge tree your dead.

16's and 15's have just the right amount. The E30 chassis will tell u long before the back goes, when the car is going to go. One of the signs is through the steering wheel and another is felling the sidewall flex when cornering.

Fuzzy i bet this factor had an influence in your accident the other week. The back end does not go without warning on these cars. Big wheels hinder these warnings somewhat when driving on the cars limit. Snappy back ends = prangs

Again u need a balance and with a 17 or more u do not get this balance. After all the E30 was designed to take 14's and 15's not 17's and 18's. Yes E30 M3's had big 18 inch wheels, but their suspension was designed to take those wheels. Our cars were not.

Look around at the best handling cars on this forum. All of them run 15bbs or 16' of some kind.

Que Ian 332!

I know some disagree but this is how i see it

[JOSEMI]

I also find the 15" bbs to be just perfect for my car. The handling feels full on and there is also a noticeable feeling of the road.

The handling of these cars is such that the car transmits that the back wheels are sliding, its like un unconfortable feeling that something is not going well in the back, and the steering also feels a bit 'lighter'. As Simon said above you do know when the car is loosing grip and it lets you time to rectify by slowly correcting with the steering wheel. (Edited: and reducing speed !)

I have 15" bbs on my car and, although Alpinas look brilliant on any E30, I wouldn't change those bbs. The riding with them is awesome. And they came off a 14 year old M3.

Jose

[fuzzy]

good point simon13...your probably right there mate

[oze30]

ok.. But what happens if you drive it at 7/10's, not 11/10's?

Out of curiosity fuzzy, what speed were you doing when you crashed?

[Moofles]

e30's are also snappier cos of short wheelbase ain't they?

[TOURINGDADDY]

sorry peps im gonna rock the boat here 17" are crap for handelin as i sold mine and went back to 15" and have never looked back runnin 195/50/15 and its a tourer, my sig shows the 17" looks da bomb but was shite to drive

[astondg]

e30's are also snappier cos of short wheelbase ain't they?

Really? At 2570mm I wouldn't call it short but I guess it depends on what else you drive. It isn't as long as the newer 3 series models but it is longer than quite a few other cars. I'm not sure I would call the E30 snappy either, I guess that depends on wheels, tyres and suspension.

One thing people haven't mentioned is weight. Usually 17's will weigh noticably more than 15's (notice said usually) which means more weight overall and more unsprung weight which is going to effect handling too.

I have 16's on my 323i with 205/50 tyres after having 15" BBS style wheels and 205/55 tyres and I am sticking with the 16's. My 16's are also lighter than the 15" BBS (6.5kg Vs about 7.5kg).

Personally I think 55 profile is a bit high and 45 is a bit low (depending on width of course) so the 50 is about right. It gives sharper steering and better handling without compromising the ride and handling on bumpy roads too much. That all depends on how the suspension is set up to, if you have the suspension set up right 17's could ride just as well as 15's (like on newer cars).

Aston

[Moofles]

i don't really know how it compares to other cars, i am actually reciting info that karan mentioned once when i was asking him about how easy it is to drift an e30...he mentioned that the short wheelbase doesn't help. No-one else has said anything though, i don't think it's short enough to make people complain!

[oze30]

OK.. So for someone that does thrash the crap out of my car, and just want it to look good, stand out and handle better ( I'm a granny driver especially on lanes.. sticking to the limit. No drifting, so boy racer stuff, just normal day to day driving. Highway miles and some lanes.

15's or 17's?