I am debating on tire size for couple of weeks now. I am going to 20" from 18". I currently have 235/60r18. I am debating between 245/50r20 or 255/45r20
Wheels are 20×8.5 offset 35. I am wondering if the wider 255
Might be too much for the front end and if the 45 series profile will be too hard.

 

It may be but it depends on the tires as much as the increase to 20s. Are the 245/50r20 or 255/45r20 both the same overall diameter and the same diameter as OEM? You may find one size has far fewer tire options than the other.

I have 8 inch wide wheels with 255/50/19 tires and after 2 years there has been no damage to the front end from them. If you go wider you will the increase in traction. However the 45 sidewalls are more likely to get damaged by potholes as the sidewall is narrower. So the 50 sidewalls on a 20 inch tire may be safer if the roads are bad in your area. I have 45 tires on my other Lexus and had 3 tires damaged by potholes at different times.

The ride is a little stiffer with Goodyear Eagle F-1 Asymmetric All-Season Tires which have been great with sharp steering, good grip and wet traction. I suggest you call www.tirerack.com for advice on tires that fit your profile.

 

255/45r20 seem to be more common. In live in NYC and 50 series would be more preferable

 

Tire Rack has lots of tires in 245/50/20 Read the reviews and tests to see which ones you like https://www.tirerack.com/tires/TireS...earDiameter=17

They will ship to your installer, or sell you wheels too with the tires already mounted.

Maybe you should just go to 19 x8 or 8.5 wheels and get 255/50/19 and then you won't have to worry about NYC pothole wheel damage as much. It is still a big improvement over the 235 width stock tires and the wider wheels make them even more effective.

 

I decide to go with 245/50r20. I plan to mount them this weekend. Will post some pic