mixed tyre makes on the rear

[Mr.FixitNorm]

Hi All, I'm new to the forum, just wondering if any of you have any experience of mixing tyre makes on the rear of a porsche 944 causing excessive tyre noise?

My car is a 1988 944s with 17" Boxster wheels all round, when I bought it 18months ago it had Continental Sport contact 2's on the front and the rear has a 255/40 ZR17 Pirelli P zero N3 on the offside and a 255/40 ZR17 Continental Sport Contact N1 on the nearside. Both tyres have about 5-6mm of wear left and the tread is even.

About 6 months ago I thought I noticed a slight droning noise when in a straight line or going round long right hand bends, but the noise seems to go when going round a left hand bend ! Speaking to friends etc the general consensus was front wheel bearing. I changed the inners and outers on both sides at the front , but the noise is still there. I've had the car up on the ramps at my local ( trusted ) garage and me and the owner checked all the anti roll bars/bushes etc and also jacked up the wheels to check for rear bearing noise or wheel play - result nothing in fact the garage owner remarked what a good condition everything seemed to be in.

He did suggest that the different tyre makes may be the cause ( he has had this once with Bridgestone tyres )

I am planning to swop them round but before I do has anyone experienced this before or is it a red herring.

Any help or ideas gratefully accepted.

Norm

 

[Super_Marv]

Could be saw tooth wear?

 

[Suffolk944]

Hi and welcome to the forum []. Not so sure about the odd tyre theory as a source of the noise but swapping them must be worth a go to see if you can find a cheap fix before exploring potentially more expensive cures.

 

[ukmastiff]

To answer the specific question ( as opposed to is it a good idea [] )
no it can't cause excessive noise.

Regards

Mas

 

[zcacogp]

As Mas hints, mixed tyres across an axle is not a good idea on any car, let alone on the (driven) rear of a Porsche.

I'd get a matched pair on there as soon as possible for a bunch of reasons, and if that doesn't solve your drone problem then try other things.


Oli.

 

[Dave S]

What he said ^

Dave

 

[Mr.FixitNorm]

Thanks for the reply's, I must admit I've never been happy with mixed makes on the same axle, but I haven't experienced any handling problems in the eighteen months I've had the car, possibly due to the tread pattern being very similar, but I think now's the time to get rid of the Pirelli and have the Continentals all round.

I'm probably going to get flamed for this but as there's a good 5-6mm of even tread left on both tyres, and finances don't allow for two new tyres, I'm going to try and find a good part worn to match the existing sportcontact.

There seem to be quite a few places out there selling good quality part worns, but I'll steer clear of any private e-bay sales!

I will try the swap round first to see if it does make a difference though.

--Super-Marv - could you expand on `Tooth wear' for me please?

ATB

Norm

 

[Mr.FixitNorm]

Hi Jon, meant to ask are you anywhere near me ? I'd love to meet up with any local 944 owners in my area ( Lowestoft )

ATB

Norm

 

[pauljmcnulty]

Welcome!

What all the above said. []

I'm not sure about there being a problem with mixing decent tyres on the same axle but for the relatively small cost it's worth getting both replaced and balanced.

944s are noisy around the rear, wind noise, bearings, gearbox, driveshafts etc. You are running 17"s, pretty much the limit for a 944 and if it's over-tyred there is bound to be more wear on all the main components. I'd get someone to come out with you to see if they can help pinpoint the noise.

 

[david924s]

My S2 started droning a year ago and I thought it was worn tyres at first then it developed and was recognisable as front wheel bearing needing replacing might be worth checking these as well as matching the tyres.

 

[Mr.FixitNorm]

Hi David,

That was my first thought, I changed both fronts ( inner & outer ) a couple of months ago but it didn't seem to make any difference. Nice thing is it was relatively cheap ( £55 the set ) and only took me about 1½hrs []

ATB

Norm

 

[Super_Marv]

I've got a bit of saw tooth wear on the offside front of my 968 at the moment. Makes a slight droning noise at high speed in a straight line or when I'm turning right at high speed. Basically,the tread has uneven ridges in the blocks. I've had it on my Golf before too, and there was flat spots of tread about 15cm across. Almost turning the inside of the tyre into a 50p piece!

It's worth removing your wheels and inspecting the tyres closely. It usually requires close inspection to notice the anomalies in tread.

 

[Suffolk944]

ORIGINAL: Mr.FixitNorm

Hi Jon, meant to ask are you anywhere near me ? I'd love to meet up with any local 944 owners in my area ( Lowestoft )

ATB

Norm

Hi Norm,

Not too far away - Ipswich. We will have to organise an East Anglian 944 posse ! []

 

[jasonp]

ORIGINAL: Suffolk944

ORIGINAL: Mr.FixitNorm

Hi Jon, meant to ask are you anywhere near me ? I'd love to meet up with any local 944 owners in my area ( Lowestoft )

ATB

Norm

Hi Norm,

Not too far away - Ipswich. We will have to organise an East Anglian 944 posse ! []

hiya jon.i would be up for a meet in the east anglia region, please keep us posted, regards jason p

 

[Mr.FixitNorm]

Hi Super-Marv,

Your's was a timely reply, I phoned a small tyre dealer today to see if they had any part-worns in the size I need ( they didn't ) but got talking to the guy about the noise and he said exactly what you said !!

I'll definitely change the wheels round this weekend , that should hopefully identify if it's the problem.

I'd love to join in an East Anglian meet up too!

Norm

 

[Super_Marv]

Let us know what you find Norm!

It probably goes away when you're turning left, because of the slip angle of the tyre, as you turn left unloads the part of the tyre, which has the saw tooth wear.

(Google tyre slip angle to see what I mean!)