ABS has got NOTHING at ALL to do with the tyre size. ABS just senses that when the car is abt to skid. thats it. it can get activated at even 20 km/hr and it can NOT get activated at even 160....tyre size has nothing to do with ABS..and 2 percent difference is nothing at all.
and why not 195 ? cause there is no need. City is an economical car and 195 would affect the economy of the car as compared to 185. yes, i wud have had gone for 195 if the car had handling and braking issues, but even with the stock tyres, both are outstanding. in case of a corolla, i definitely would go for 195. i even agree with the stock size, but the problem is that Yokohama Advan db is not available in 175, thats why i m going for 185. as Advan db has less rolling resistance, is super quiet and is made of compound made for fuel economy, even its 185 wud be more economical than the stock 175. i mentioned somewhere in this post earlier, and i repeat here, that DO keep in mind that these are the tyres which are coming as stock with Toyota Prius Hybrid car, a car which is designed for the very purpose of attaining max fuel economy, and it comes with Advan db. so u can well imagine how gud these tyres must be. rest, ur choice