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I'm about to get my 159 2.2 JTS and I've already purchased all the required stuff to turn her into a Ti (..could not find a proper Ti - ready). The conversation around the use of 19" wheels is resulting into a major impact both in performance and av. consumption.

If I take account my own experience from my 156 1.6 that had 15" wheels and I installed the 17" ones, I remember that I did have a slight performance issue but the consumption was all the same - of course the car is lighter.

Therefore and since I do not have a lot of first hand experiences from friends, what's your opinion on the matter? It is just I do not think that Alfa Romeo would be offering a Ti version that would affect everyday use that much.

Thanks for your time.
 

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The rolling radius difference between a 19" rim and a 17" rim is only a couple of percent. Not enough to impact consumption negatively. Remember your tyre wall height changes between rim sizes which absorbs the extra bit the wheel gains.
 

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The rolling radius difference between a 19" rim and a 17" rim is only a couple of percent. Not enough to impact consumption negatively. Remember your tyre wall height changes between rim sizes which absorbs the extra bit the wheel gains.
So basically, going from a 225/50/17 to a 235/40/19 (if I remember correctly the Ti specs) is more or less, the same?
 

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yes. that is an RR of 343.4mm vs 335.3mm or -2.36% so your speedo will reckon you are doing 70Mph when you are actually doing 68.35mph.

Tyre size calculator

Easy enough to do the math.
 

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My 159 is a factory TI and came with the 19s. Over winter however I run it with 17" Genuine 159 Multispoke wheels, shod with the correct 225/50/17 winter spec tyres, and I can honestly say I've noticed NO difference in fuel consumption whatsoever.....

The same also applies with the 19" Prodrive wheels fitted with the larger 245/40/19 tyres....I've noticed no difference.

As Jay has already stated, speedo readings WILL be effected slightly. According to my GPS/Sat Nav, when I'm on the 17s, the indicated speed is approx 2-3mph UNDER the actual speed according to the Sat Nav. When running the 19" Ti rims fitted with the factory specified size 235/40/19 tyres, indicated speed is approx 1mph UNDER actual speed according to GPS. And finally with the 19" Prodrives fitted with the larger 245/40/19s, indicated speed appears to be BANG ON accurate according to the sat nav! Although this is nice, you have to remember when driving with these tyres, there is little to NO room for error when approaching a speed camera!

Normally all/most vehicles are calibrated for the Speedo to overcompensate the actual speed you are doing, to allow for such error! lol

CS
 
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