right now i have some 225/70/R15's and tomarrow i'm going to get some 235/75/R15's my question is is the new tire going to be wider i need to know because i have helper springs on the rear of the cherokee and the clamps for them are about a inch away from the sidewall of the tire and i don't want to go to get them put on to find out that i need to grind the clamps down a bit. i found a website with these numbers for width but i wanted to check with you guys first to see if they are accurate

225/70/R15's is suposed to be 6.3 tread width

235/75/R15 is suposed to be 6.1 tread width

Do these sound right?
http://www.angelfire.com/on/geebjen/tires.html

This is the webpage

 

a 235 is 10 mm wider then a 225 so in theory it should only be 5mm closer to the clams then it is now. tread pattern and such can affect it but i'm gonna say you should be safe

 

i found another tire size calculator that says that the 225 sidewall is 6.2 and the 235 is 6.9 So i guess that is a difference of .7 inches and if you divide that by 2 that is .35 on each side of a inch. I'm sorry but im bad at math and conversion but since i have a inch of clearance that isn't even half a inch so i should be good. Does this sound right?

 

225/70/15 = 225mm (tire width) /70% of 225mm (sidewall height)/15"rim sizing
235/75/15 = 235mm (tire width) /75% of 235mm (sidewall height)/15"rim sizing

Your new 235/75 will be slightly taller and wider.
If you've got an inch to spare you should be fine.

Old tire
sidewall=6.2"
radius=13.7"
diameter=27.4"
225 tire is 8.85 inches wide
70% of width is 6.19 inches tall sidewall

new tire
sidewall=6.9"
radius=14.4"
diameter=28.9"
235 tire is 9.25 inches wide
75% of width is 6.9 inches tall sidewall

Difference of width between tires is 0.40 inches.
Divided by 2, that's 2/10ths of an inch closer to your bracket.
I think.....