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Discussion Starter #1
I have fitted 225 40 19s in the front rather than 235 40 19 on my 159 TI 2.4 Qtronic and 255 35 19s in the rear. All Michelin Load rating for the front is 93Y

Has anyone done this. What do you AO members think about this. I have no problem swith th 255 35 19s they look much better from behind and side view plus they hold better. The reason I put 225 in the fron is because its easier on the steering and cheaper. Plus BMW's use this size aswell.

Whats the ups and downs. do any of you know.

Last thing is whats the correct pressure for these sizes.:rolleyes:
 

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No response to my reply in the other thread where you posted the same question..... hmmm.

So,
225/40R19 Fronts
255/35R19 Rears

On a front wheel drive car........ surely you can see the problem there?
 

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Just going on the facts and sparing you my opinion;
*A load rating of 93 is too low
*255 is too wide for an 8J rim
 

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Bmw is a rear wheel drive hence the larger tyre on the back, dont know how your cars going to handle with that set up .
I think i would be taking advice on this cant see your insurance company agreeing with these different tyre sizes.
 
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Discussion Starter #5 (Edited)
the 255 sits just fine on the rims, so I dont see a problem with that. Why would wider tyres in the rear effect handling, rear tyres take control of the car over 70 MPH so wider the better isn't it. What type of a problem would having a lower load index cause, I seriously do not know, can you help me on this.

Regards to the insurance. With my BMW I modified all tyres and rims and had an accident insurance company said nothing
 

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a 255 tire is 10" wide which is 2" wider than an 8j rim. for such a low profile tire the sidewalls will be under a great stress and might lead to premature wear of the tire or even worse...
 
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Discussion Starter #10
Didn't know the Q4 had 8.5J wheels, does it.
So do any of you AR owners know what the PSI should be for my tyres
 
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Discussion Starter #11
No response to my reply in the other thread where you posted the same question..... hmmm.

So,
225/40R19 Fronts
255/35R19 Rears

On a front wheel drive car........ surely you can see the problem there?
David, thanks for the reply, so what would go wrong or whats the downs of putting these tyres
 

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understeer.

:)
 
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Discussion Starter #15
Mate, if you had a 1970 Dodge Charger and were using it on Santa Pod, then I'd say this is a good idea, as however you have a FWD car, then not only is there no point in having larger wheels on the rear, but also the car will not handle like it's meant to, you are meant to fit the correct tyre size to your car bud, these are clearly not correct.
 

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The load index is based around the weight/mass of the car. If you fit a lower indexed tyre it won't have the sidewall strength that is required for that weight of car. This can result in the tyre wearing quicker, or in extreme case, ie if you drive hard and fast, they will give way and blow out.
Some cars need XL tyres, meaning a higher number on the rating.
I would imagine that a heavy car like the 2.4 will need XL tyres.
Your car weighs 1630 kilos unladen, which is heavy!
The manual states you need 235/40R19 95Y tyres. The 95 means that each corner can hold 690kg. The Y means they are suitable for speeds upto 300km/h.

There is a real issue with the insurance side of fitting non-regulation tyres. Especially if the speed and load ratings are out. Imagine one of your fronts lets go at speed and you total the car. The insurance company would find this loop hole and you would get nothing off them. Gulp.

Not a risk I would take really. Check the load and speed rating of these tyres first.
 
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Discussion Starter #17
The load index is based around the weight/mass of the car. If you fit a lower indexed tyre it won't have the sidewall strength that is required for that weight of car. This can result in the tyre wearing quicker, or in extreme case, ie if you drive hard and fast, they will give way and blow out.
Some cars need XL tyres, meaning a higher number on the rating.
I would imagine that a heavy car like the 2.4 will need XL tyres.
Your car weighs 1630 kilos unladen, which is heavy!
The manual states you need 235/40R19 95Y tyres. The 95 means that each corner can hold 690kg. The Y means they are suitable for speeds upto 300km/h.

There is a real issue with the insurance side of fitting non-regulation tyres. Especially if the speed and load ratings are out. Imagine one of your fronts lets go at speed and you total the car. The insurance company would find this loop hole and you would get nothing off them. Gulp.

Not a risk I would take really. Check the load and speed rating of these tyres first.
Thanks for the info Wynne. Going back to standard next time.
 

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Also, the handling set up on the car is now compromised.
The fronts will let go before the rears due to the smaller size, especially at lower speeds.
I wouldn't be comfortable with this set up at all. At the very least swop fronts for rears to re-dress the balance.
 
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Discussion Starter #19
Basically the fronts are too narrow now and the rears are way too wide, get 'em swapped round mate, as Wynne71 says it will redress the balance and your handling should be alot better. Obviously being too narrow on the front loses you some grip which is going to cause severe understeer otherwise.
 
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Discussion Starter #20
Handling wise I have pushed it hard and its seems ok. But you guys are right its best putting it back to standard spec.

The only thing with the standrad spec is that, their arent much choice with the tyre brands.

Is there any other size setup that I can use. I want to put Vredestein.
 
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