Tyres for standard 15inch BBS wheels?

[Stu_B]

Hi All,

I want to replace the tyres on an E30 325iS, it has the standard 15 inch BBS wheels.

The current tyres are 205/55/15 - firstly, is this the correct size?

I notice 55 profile tyres are always expensive, do people use 50 profile instead perhaps, and if so what effect does it have on the speedo as this is currently quite accurate.

I use Uniroyal Rainsport and Rallye tyres on my VW's and am always very happy with them, are these a good choice for the E30? Any other recommendations? Also - where to buy them, usually use mytyres.co.uk - any other good (cheap!) places?

Any help much appreciated

Cheers
Stu

[orangecurry]

Hi All,

I want to replace the tyres on an E30 325iS, it has the standard 15 inch BBS wheels.

The current tyres are 205/55/15 - firstly, is this the correct size?

yes

I notice 55 profile tyres are always expensive, do people use 50 profile instead perhaps, and if so what effect does it have on the speedo as this is currently quite accurate.

some people do - 5% out?

I use Uniroyal Rainsport and Rallye tyres on my VW's and am always very happy with them, are these a good choice for the E30? Any other recommendations? Also - where to buy them, usually use mytyres.co.uk - any other good (cheap!) places?

Any help much appreciated

Cheers
Stu

In that size I've got NCT5s, which are too hard but OK, and Rainsports, which are good.

People rate the toyo T1-R, but I've never tried them - I'm sure there'll be a lot of options along in a minute.

[handpaper]

Just (an hour ago!) fitted a new set of T1-Rs, 205/50/15

50 profile tyres have shorter sidewalls which flex less under cornering for more precise handling.
Speedo will overread by another 3% vs 55 profile - but you can fit 55s on the back if you want to avoid this; lower profile on the front makes more difference.

Toyo Proxes T1-Rs are an excellent tyre for the money, they're very good in the dry (unless you overheat them ) and even better in the wet. The only downside is that they will wear fairly quickly (15k from my fronts), but that's a price I'm willing to pay for the level of grip they provide.

[Stu_B]

Thanks for the replies, any ideas on costs of the Toyo's? Where did you purchase them?

How do they compare in wet weather to the Rainsports, I've found those very good on my other cars you see?

[orangecurry]

IMHO

www.mytyres.co.uk

89V 46.30 GBP each all in P&P VAT everything

rainsports 86V 51.80

[jaistanley]

No no no no no no no no no fitting different tyres front and rear (if you can help it). It's not going to make a huge difference but it WILL make a difference to the handling of the car.

Jai

[Brianmoooore]

No no no no no no no no no fitting different tyres front and rear (if you can help it). It's not going to make a huge difference but it WILL make a difference to the handling of the car.

Jai

Possibly, but not necessarily detrimental.
Get the rolling radii to far different ,though, and you'll upset the ABS.

[jaistanley]

Primarily: slip angles are different, then there's the difference in unsprug, scrub radius (closely linked to slip angles), compliance (causing grip on rough surfaces being different front to rear) and differing modes of vibration around the tyre's surface (an nvh thing).

Like I said, it wont make a huge difference but the thing with tyres and brakes is you dont notice until you reach that last 0.1%; which is exactly when you want things predictable!

I'm being a little hard line with all the 'no's, I doubt anyone will go to hell for fitting different front and rear profiles.

Jai

[oakey]

Primarily: slip angles are different, then there's the difference in unsprug, scrub radius (closely linked to slip angles), compliance (causing grip on rough surfaces being different front to rear) and differing modes of vibration around the tyre's surface (an nvh thing).

Like I said, it wont make a huge difference but the thing with tyres and brakes is you dont notice until you reach that last 0.1%; which is exactly when you want things predictable!

I'm being a little hard line with all the 'no's, I doubt anyone will go to hell for fitting different front and rear profiles.

Jai

why do most supercars have different different profile tyres on front and back?

[orangecurry]

they don't... or do you mean the percentage is different? If a car has wider tyres at the back, the front tyres will have a different profile percentage from the rears, but the profile itself will be the same.

[oakey]

they don't... or do you mean the percentage is different? If a car has wider tyres at the back, the front tyres will have a different profile percentage from the rears, but the profile itself will be the same.

ahh i see

is the profile size stated on the tyre a percentage measurement of the width then?

[orangecurry]

you got it

so to take an E30 example

205/50/16, profile is 50% or 102.5mm
225/45/16, profile is 101.25, so near as dammit.

[oakey]

well....
the ferrari testarossa, when brand new, came with 225/50/R16 fronts and 255/50/R16 rears. so doesnt that mean that the rears are actually a bit chunkier than the fronts?

[oakey]

sorry i meant the fronts will be a chunkier than the rears

[oakey]

lamborghini countach comes with these tyres from new- Michelin XWX 205/70x14 front tyres and Michelin XWX 215/70x14 rear tyres.

[orangecurry]

yes but what do Italians know about driving?

and it was fashionable to have different sizes in the 1970s

[jaistanley]

Also, the cars were designed with a tyre size in mind. You can adjust suspension geometry to counteract adverse affects from elsewhere.

I'm not saying it's a bad practice but it IS bad practice to stray from manucaturers geometry. If you have to (like I am when fitting 17"s over my brakes) then do the same to the front as the back, left to the right. At least then the %'age you change the geometry is the same all round leading to predictable handling)

Jai

[Stu_B]

IMHO
www.mytyres.co.uk
89V 46.30 GBP each all in P&P VAT everything
rainsports 86V 51.80

Thanks - I can't find Rainsports in 205/55/15 on mytyres, only Uniroyal Rallye 550's at £58.70 each? Any ideas?

[orangecurry]

strange - they were there last week.

If I were in your position, I would buy the Toyos.

[Stu_B]

strange - they were there last week.
If I were in your position, I would buy the Toyos.

No worries - thanks for the info