Optimal tire size and width for E21(new rear tires question)

[croma_man]

Ok, everytime somebody opens this debate when we come together with a beer, we end up screaming at each other

so the question is, fast road setup (E21 / E30), which tire size is optimal for a 200hp+ car ?

I'm driving 195/45/16 on 8" width on the front and 225/40/16 on 9" width in the back. But everybody keeps telling me the tires are too wide, I don't agree with that.

Mates keep telling me I would be driving faster with 195/55/15 ...

I know if I'd go on a trackday, I'd put on 15" and race slicks.

So how to close this issue we have? Or somebody will end up with a black eye

[Jeroen]

I guess this is about finding a balance. Tyres that are less wide give less resistance, but also less grip. I'd say use 205-225 series in the rear with 200+ BHP and with higher sidewalls like on 205/50-15's may make the car slightly more easy around the limits of grip compared to lower examples like the 225/40-16's. 195/55-15's would be too much sidewall to my liking though. For road and occasional trackday use I personally find 195/50-15 fronts and 205/50-15 rears a pretty good combo on an E21, preferably the same make and model tyres front and rear though.

[nas80]

I have about 240hp (roughly) and in my experience a lot of this isn't about tyre size, its about tyre composition / lsd / geometry / power delivery and driving style etc.

I get along just fine with toyos t1r's on a 195/50/15 all round, they are a soft tyre so i get plenty of grip when launching and coming out of bends.

[polov8]

Just had this same dilemma. To go on my 7x15's I got 195/55 15 and 205/55 15. The stock tyre size being 185/70 13, that makes the rolling diameter 589.2mm

195/50 15 is 576mm -13.2mm
205/50 15 is 586mm -3mm
195/55 15 is 595.5mm +6.3mm
205/55 15 is 606.5mm +17.3mm

I figured that a bit of sidewall is a good thing on a 30 year old car with the lousy roads round here, and it also will keep the arches filled out and mean it won't need lowering as much to look right, and that means more suspension travel and a better ride. and the bigger rolling circumference means the overall drivetrain ratio is a bit taller, which on my car is a good thing!

I figure

[croma_man]

hmm, interesting, I guess I'll have to take 2 sets with me next time on the trackday and bust this myth

[TopCat]

Herman has around 261 bhp and had 195/50/15 Federal RSR595s all round

I have gradually replaced with 205/50/15 all round in same tyre and compound.On standard Alpina Suspension albeit with a slight ride height increase 1/2 inch for reasons I won't bore you with.

Only tried the 195 on the front in competition and they do feel slightly undertyred- I have seen B6s in Germany wearing 205/50/15 front and 225/50/15 rear. On bumps it is more of a feeling of running out of options limited wheel/suspension movement and limited sidewall leading to the inescapable feeling that you have a helluva lot of engine set well forward in an E21.

I prefer to drive on the rear to settle the car so you know what may happen post Apex- of course it is more difficult to drive on the rear if the rears are larger!

Each time I try to learn more in Herman either the track day is wet (learn nothing re this ) or Herman manages to break down mid event.

[polov8]

Price is another pretty big factor, I was looking at 225/50 15's, but anything good was looking like being £150 or more. 215/50 15 seemed like a sensible size, but options on that are terrible, despite being the stock ur Quattro size.

[TopCat]

Toyo 888R do a 215/50/15 I think???

[polov8]

yeah, I daily my car rain or shine, 888R's aren't going to cut it on an icy roundabout! And they aren't cheap either

[e21-Mark]

Used to run 195/50x15 Toyo r888 on MIB and only thing they didn't like was standing water. Used them through the Winter (inc snow) and they were better than I expected. Expensive is anything wider than 195 though. Silverstone do a good, road legal alternative track tyre.

This time I have gone for Marangoni Zeta in 205 & 215/50 but had to have the arches dressed to get some more clearance.

[Duracel79]

My track tyres are R888's:

Front: 215/50/15 on a 7" rim
Rear: 225/50/15 on an 8" rim

Just got some new road tyres (Falken ZE914) yesterday in:

Front: 205/55/15 on a 7" rim
Rear: 205/60/15 on a 7" rim
V rated (speed), C (economy), B (wet grip), 70dB (noise)

Regards

Ben

[TopCat]

Has anyone heard a rumour of new EU Regs that will shortly come into force banning track type compound tyres for Road use? Made of the "wrong" sort of dirty oil.............?

Come on ye Dutchmen? Do you know?
- I know how much you guys love the EU central control!!!!

[Jeroen]

Hahahahaaha nope, haven't heard any rumours of that kind. Sofar track type compound tyres are ok to use and I love the Toyo R1R's on my 320iS, they're even pretty good in the wet. For me that's a great tyre for fast road and trackday use. I usually get the car out on better days but if I go on a holiday I'd like to have some decent grip when I encounter rain as well and the R1R has proved to be a pretty good choice there. For everyday use I'd prefer a tyre that does better in the rain though.

There aren't too many regulations on tyres here, for Dutch MOT they look at profile depth and they shouldn't be visibly dried out. Funny as I'd prefer to have more strict regulations like on DOT code or something. People are driving around on tyres 12 years old but as long as above requirements are met, they are considered ok. Which imo gives a false feeling of safety as the rubber has already hardened out to such an extent that tyres are already seriously dangerous in the wet.

Believe they are more strict in some other countries like in Germany where from some point winter tyres are mandatory and there are limitations on size (over here any size is ok as they don't rub the fenders). But I don't know the details of foreign regulations.

[croma_man]

looking for new tires in this dimension 225/40/16

new stock, older stock...just better than the crappy T1R, falken ziex and uniroyal which are the only ones that I can buy new. Looking for Yokohama, continental, dunlop, pirelli...

Currently I have Continental sportcontact 2 on my E21, but can't find new ones anywhere.

I also tried the 215/40/16 on the 9" width but for my style of driving, its overstretched.

Please help, if anyone knows about something, payment paypal, and I can organise the pickup.

[nas80]

http://www.mytyres.co.uk/cgi-bin/rshop. ... hen=Ordern