S60 Rear tyres

[chrisy]

My rear tyres are 225 45 17 91w Nexen and they're noisy.
Can I fit 245 40 17 on the rears? Will these affect the ride ?
I have 4 Contis Sport Contact 5 so was thinking of have these fitted on the rear.

[N11BOT]

I would defiantly avoid mixing tyre sizes even between front and rear axle.

(Tyre wall height) x (aspect ratio %) = (tread width)
225x 45% = 110.25
245x 40% = 98

The issue is well expressed here: http://www.tirerack.com/tires/tirete...jsp?techid=136

I would be resistant to downsizing the tyre's tread width (reducing grip in all situations) and go instead for a different brand of tyre which may well be less noisy in operation.

I rotate the tyres from new after 15,000mls and usually expect to replace a full set at 30,000mls (however, as the fronts wears differently to the rears, there may be some reduced grip or unexpected handling characteristics for up to 500mls or so after when worn tyres have been rotated (but I have not found I can significantly detect it in normal road use).

Inexplicably my tyre supplier fitted the wrong size of tyre to one front wheel (narrower tread by one size) when I had a new set - apparently wrong tyre delivered to them and they did not check.

I defiantly found the car had a lack of grip under acceleration especially in the wet and some deterioration in cornering grip but braking distance and stability felt fine. I had put this down to the cheap Chinese brand I decided to try - half the cost of EU/US brands. At MOT the car was failed and an embarrassed tyre centre fitted the correct sized tyre. The improvement in grip was considerable.

[chrisy]

Thanks for that.
Im not fully convinced that I cannot fit 245 40 17 on my rears. I have seen a S60 T5 with these tyres so it can be done with the wheels as mine. I have to check my user manual and with a Volvo Dealer.

[chrisy]

I've never had other tyres than Continental or Michelin Sports on any of my cars for years. I am Mercedes owner for the past 15 years so I know the brand very well. I do not feel 100% safe with these Nexen tyres....

[N11BOT]

Originally Posted by chrisy

I've never had other tyres than Continental or Michelin Sports on any of my cars for years. I am Mercedes owner for the past 15 years so I know the brand very well. I do not feel 100% safe with these Nexen tyres....

Well I had no experience with these cheap Chinese tyres and could not find any good reference to other people's experience with them. But since my tyre centre said that if I found they were not up to the job they would credit their value against my purchase of a set of well known tyres I had no reason not to give them a proper try-out.

What I did learn, from the trade rep, is they are made with the same materials quality, production machines and manufacturing facilities/locations as many known brands are - made in the same factories in China as many known brands who contract some production to these factories. These factories also invent their own brands just for selling tyres 'on price' (and they end these budget bands too before it becomes known to offer quality tyres and a fraction of the price of the famous brands they manufacture for). That could be bunk - who knows?

My verdict is they work just fine for my driving style - which, when not towing a car transporter, sculling-boat trailer or fully loaded with family, luggage and 4x bikes on the tow-bar, is - shall we say - ongoing and progressive!

But I reckon at least 50% of this sort of car stuff is 'in ones head' anyway!

As regards reducing the tyre width, the narrower tyre may well be an applicable size for the car, and it may produce more economy too, but by simply physics it is going to offer reduced grip under braking and cornering. And if you have substantially different tyre performance on the rear to the front you are going to get a different dynamic to that the factory anticipated when designing the vehicles suspension geometry. Well that may not trouble you too much - at least up until you have to 'stand on the brakes', cornering on a wet road and at high speed. Then you will want everything going for you me thinks!

Back to your original question. The taller narrower tyre may well improve the ride comfort, as the tyre wall has additional flexibility, but the advantage of the tyre with the lower side-wall is that it has enhanced handling characteristics - albeit offering a slightly harsher and nosier experience.

I would think if you want to use the tyres you have - if they are a valid fitment for the type and model of car - you will do better to just fit the set of 4 tyres.

[chrisy]

Thanks. Much appreciated.
Just got back from 3 tyres shops and was told the same: I can fit 245 40 17 on my rears without any problems. It won;t be noisier , it'll improve the handling, braking and they're silent.
Chinese quality is 1000% different to german quality. I stick with ContisSp5.