1997 3500 4x4 dually. Stock tires and spare are 215/85/16. I want to go to either 235/85/16 or even better 255/85/16. Do I need to change the spare tire too for either of those sizes, or can I keep the 215 and it'll be like a donut spare?

Thanks for any help

 

You really only need it i unless you blow out a front tire, but then your differential will adjust for it, which isn't a big deal if you are gonna repair or replace it quickly.

215 to 255 is only 40mm in height divided by two is 20 mm total taller. 85% of 20 is only 17mm wider.

I wouldn't worry too much about that.

 

Okay, thanks for the reply.

 

Going with spacers for the rear 255 tires?? I think the max is 245 without the rear tires touching..

 

Was with a friend who was running 35's when we got a rr flat 100 miles into the unknown, we threw the stock spare onto it and was amazed at how well it drove even with his limited slip rear end!

 

Dave, I'm undecided about spacers. There's different ideas about it from what I read, some say you only need them with certain brands. I definitely don't want to take a one ton truck and make it any less useful by not being able to load it. I wonder how 255's would look with a spacer? I'd probably go with a 2 inch so I don't have to cut studs. Might look strange, although I think it looks good with 285's.

Joem, thanks for the story, makes me feel more confident.

 

I have 305's and looks, quit and get's good traction and no mod's