[Pri]

Hey guys,

I currently have 215/45z/r17 tyres but want to reduce the gap between the archs and tyres. I want to avoid lowering or getting 18s so I thought the simple solution would be to get bigger width tyres.

Has anybody done this or have a picture so I can compare the differences? Struggling to find pics of GT's on non low profile tyres.

Thanks

Pri

 

[David C]

225/45R17 should be fine.
They were the std size for the 3.2V6.

 

[Pri]

Thanks David.

From what Ive read this morning, if I increase the width of the tyre to 225 and leave the profile at 45, will that not leave the gap between the arch and tyre the same?

Thanks

 

[daryl]

Check your car model I.e. Blackline, lusso etc on the Internet, I had 225/45 on 17s and they were too wide so they were rubbing against the suspension arm. Had to buy a new full set of 215s.

 

[David C]

From what Ive read this morning, if I increase the width of the tyre to 225 and leave the profile at 45, will that not leave the gap between the arch and tyre the same?

Don't know what you have been reading, but that is wrong.
The "45" is a percentage of the width, so 225/45R17 are a taller tyre than 215/45R17.

 

[Quadrofoglio]

I think the OP is talking about fitting olde-fashioned 'high profile' tyres is he not, rather than wider ones? That wouldn't work would it?

 

[David C]

I think the OP is talking about fitting olde-fashioned 'high profile' tyres is he not, rather than wider ones? That wouldn't work would it?

He did say "bigger width" though.

If you go for something else you are then into tyre that are not officially approved for the car at all, like 205/50R17, which are narrower but taller.

Clearance for 225/45R17 depends on exactly which rims you have and also the make & version of tyre used. Some are wider than others, despite being the same size.

 

[Pri]

Sorry for any confusion guys...I am referring to having standard tyres opposed to low profile tyres on the motor.

 

[oozeman]

Check your car model I.e. Blackline, lusso etc on the Internet, I had 225/45 on 17s and they were too wide so they were rubbing against the suspension arm. Had to buy a new full set of 215s.

Hi Daryl,

I have 18"Ti alloys on my GT - they were on when I bought it - wearing 225 40 ZR 18s.

The gap between tyre and suspension arm seems very small - how did you tell it was rubbing?
I'm getting bad tramlining which may be down to slightly buckled wheels - I'm getting them seen to soon, but wondering if I need to change to 215s?

Also the 40s are feeling every bump.....

 

[David C]

225/40R18 is the correct 18" size, so no don't try 215...!

 

[Guest]

I have the standard 215/45's on my lovely 17 x 7 Alfa thin spokes. I'm putting a new set of tyres on soon and my favourite is Uniroyal Rainsport 2 but they do not do this size except for XL reinforced (which in my opinion are about as pleasant as the black death, lumbago, run flats or syphilis or all of these together).

The only options appear to be 'Carlos Fandango Superwide Wheels' aka 225/45's which will surely slow the steering down noticeably or 205/50's ('the cigar with 6 appeal') as suggested by David C. Whilst these surely would quicken the steering rather than slow it down, i'm a bit concerned about the fitment as the existing ZZ3 215's are barely any wider than the wheel rims. Do the wheel rims stick out wider than the tyres with 205/50's or is it not really visible and who cares any way if they steer better than the 225's ?

 

[andypj]

XL tyres refer to the load capability of the tyre. You'll notice that the load index is higher than none XL rated tyres - but that is only achieved through a higher tyre pressure. So because the car is the same mass there is no need to use this additional capability by increasing the tyre pressure and making the ride harder. Also check the load index of the 225's how close is that to the XL rated 215's? You'll find more of difference in ride comfort on the tyre makes you choose. Generally speaking cheaper tyres tend to use harder compound rubber to compensate for less sophisticated carcass construction and this will make the ride harder. Bridgestones are notorious for being a rock hard, sorry unforgiving tyre, Michelins too but to a lesser extent. Choose your tyre carefully based on what you want from it, rather than a brand or tyre that you like the look of. Also if you choose a tyre size outside of Manufacturer spec, you may invalidate your insurance. Check first rather than regretting later.

....and finally remember the actual increase in tyre width, whilst supposed to be 10mm, may be nothing at all: Some brands of 215/55/16's are exactly the same width as 205/55/16's.

 

[Guest]

Yes - I accept the principle that a reinforced tyre can be used at 33 psi for a light car like 147/156/GT, but surely it is the fact that it can be used with much heavier cars at higher pressures because it has stronger construction which gives it a more 'unforgiving ride' when compared directly with the same car, tyre and pressure but of standard construction.

As an example, the recommended load index for my 156 is 87 (545 kg), the reinforced Rainsport 2 is 94 (670 kg), which is 23%.

My actual experience of this was my Merc SLK which had XL's on when I bought it. The car was a bone shaker. When I checked the OE tyres there was no mention of XL's. One set of Rainsport 2's later (not XL) and the car was transformed. The firmer XL construction had pushed the stiffness of the overall suspension past the point of usability.

There is an old racing expression that 'half the suspension comes from the tyres'.

 

[andypj]

....and were the original tyres on the Merc Uniroyal Rainsports? because if they weren't then it may not be the fact that they were XL rated tyres that caused the problem. Yes the different construction would have made a difference but that could be because they were a different manufacturers tyre.

XL rated tyres aren't suitable for 'much heavier' cars - they were introduced to cope with people carriers - which are only slightly heavier than the car they are based on - for example a Renault Scenic is 12% heavier than the Megane it is based upon. And of course whilst the static weight is marginal it is the cornering loads that really change - so going back to your 156 JTD - which incidentally has a rather large proportion of it's mass over the front wheels - having XL rated tyres isn't really going to be the problem you expect. My wifes Mito (98bhp) was shipped with 215/45/17 91Y XL tyres and that rides much, much more smoothly than identical Mitos on Michelins and Bridgestones that were set up correctly we tried over the same course.

Just checking in the handbook, tyre load index for a JTD on optional rims varies from 88V and 91V on a 15" rim, through 91W on 16", 87W or Y on 17" and 92Y on 18"

Note also that Alfa 'suggest' Pirelli P7000 and Good Year Eagle F1's on 17" rims and Pirelli PZero Rosso on 18's and Michelin Pilot Sport 2's on a TS, JTS and JTD, Bridgestone SO2's on a 3.2

I wonder why????

Because they had a deal with those manufacturers may be or because these were the ones that performed best. I personally don't know but whatever the reason is they are prepared to endorse those products in their literature - after all they actually say 'size certified and admitted only for the specified tyre'

As I said choose your tyres carefully.

 

[andypj]

....which I suppose answers the question as to why some tyres are rubbing in 225/45/17 and some aren't if Alfa's saying only Pirelli PZero Rosso and Bridgestone SO2 are 'certified and admitted' in that size.

 

[Guest]

I am embarassed to say that the original tyres were new Capitol Sport UHP on the back (to sell it on) and 3/4 worn Dunlop Sport something on the front. So yes I entirely accept that the the massive improvement in the ride may have been largely down to binning the crap tyres.

I would say the OE 'recommended' tyres are almost certainly down to who Alfa had the deal with at the time. I have been a bike fan until fairly recently and there was a period in the early 90's when Bridgesones BT56 dual compound absolutely wasted all opposition with comparable grip (for fast road use) but double the wear. It took the big 4 several years to years to start specify them because of deals with the other tyre manufacturers had to run out.

I have also just noticed that K'fit are listing the Rainsport 2 215/45 17 XL as a 91W, same as the 225/45 17 standard ?

So i'm now 50/50 as to which to get but maybe 60/40 in favour of the 215 because they are the OE size and a niggling doubt over the 225 slowing the steering down. The SLK had 205 on the front and 225 on the rear on a 220bhp petrol car so a 225 on the front of the Alfa just seems a bit too big.

 

[andypj]

You might want to check what offset wheels you have too: if you didn't buy the car from new, the offset for the same style wheel is different for 156/147 and GT/GTA variants. This means that some will say 225's fit fine and others say they rub.

I mentioned in my previous post about our Mito having XL rated tyres, well it's interesting to note that Pirelli don't make PZero Nero 215/45/17 in non XL! It makes me wonder if the tyre manufacturers are having to make tyres to the higher standard to avoid cars being under tyred - which of course is much, much more dangerous - and also an issue for 159's with 17" wheels (but that's another story)