Tire selection help needed

[fullout83]

Ok so i have some 18x8 rims now i need help selecting correct tire size. the stock is 215/45/18 now this does fit but it is streched to its limit. would a 225/40/18 be a better fit than 235/40/18 on this size of rim? also would the 235's be too wide and could cause some roll when taking a corner hard? I am also concerned about having a nice square look, but having some rubber to protect the lip of the rim. the stockers do not do that, they are steched out and come up flush to the lip.
thanks for any feedback

 

[jbiird317]

im leaning towards the 225/40/18 because this is a much more common tire size and there are more choices available. I think that the fitment will be very similar to the stock tires on 18x8, but just a bit more "square" to the rim as you put it.

 

[bacarl]

I recommend a 235/40R18. This size is as close as you can get to the stock tire diameter-wise, so your speedo will be as accurate as possible. Also you'll have 20mm extra tire width which will help with traction. Lastly, 235 is the largest width you can safely fit without rubbing (usually). You may have to roll your rear fenders, but that's fairly easy/cheap. Without any kind of lowering springs you will most likely be completely safe.

If you don't want to have to worry at all about rubbing, go with a 225, but you won't get quite as much grip. That tire size calculator I posted in your other thread is a great tool for comparing new tire sizes to stock equipment.

edit: By the way, tire width doesn't cause tire roll-over during hard corning, sidewall height does. If you have a tall tire (like a 60-series snow tire) it will roll and flex during cornering. You can have a 300mm wide tire, but as long as it's "low-profile" it will support cornering loads efficiently. For instance, a 235/40 has almost identical sidewall height as a 215/45, and will actually corner better due to a wider contact patch.

 

[MS3077]

2.07 60ft on 225/40/18's - I get plenty of grip (rockon)

Never took the car to the skip pad though...lol!

 

[jp4130]

tire width doesn't cause tire roll-over during hard corning, sidewall height does. If you have a tall tire (like a 60-series snow tire) it will roll and flex during cornering. You can have a 300mm wide tire, but as long as it's "low-profile" it will support cornering loads efficiently. For instance, a 235/40 has almost identical sidewall height as a 215/45, and will actually corner better due to a wider contact patch.

Yes it does, if the rim is not wide enough in relation to the tire; The tires sidewalls will not be supported properly if the rim is not wide enough. imo 235 is the widest an 8'' rim can properly support.

 

[fullout83]

i am getting the mazdaspeed coilovers and rear cambers installed on tuesday so i would have to roll the rear fenders if i go with a 235. but does it not also have alot to do with the rims offset if the tire is going to rub?