I'm looking at going from 3.42 gears to 3.90 or 4.10's. I have an 04 EC/SB w/5.3 and my only mod is a magnaflow catback exhaust. My truck came with 235 70 16 tires. I have recently put on some 285 60 16's. My question is since I'm now running a shorter tire does that actually have me running a taller gear. Most people say when they put on a taller tire they are basically bring the gear size down numerically. I really want to go with 4.10's but was wondering if it would be too much with the shorter tires. Oh yeah about 90 percent of my driving is in town. Lastly, measuring my tires I get 28 inches. Does that sound about right to you guys.

 

Well im not really sure about how it would make you run a taller gear. I know you need to upgrade your gears if you decided to go with some bigger wheels and tires like in a 4x4 or something... In your situation you should have no problems. Going from a 235 to a 285 doesn't seem to be any difference you only went to a smaller sidewall. 4:10's or 3:90's should be fine with your setup
even a 3:73's would work.

 

28" tire is pretty short I would go with 3.73s or 3.90s if I were you if you care about gas mileage any.

 

If you're gonna do it, go 4:10 for performance but be prepared for a MPG hit. Otherwise you'll be wondering what you might have had because you only went 3:90. The difference is so small might as well go all the way. The tire size difference is too small to worry about in your case. I'm putting 4:10's in mine real soon. Gears are in the garage right now

 

The thing to be concerned with is overall tire diameter. According to a tire calculator, your new tires are actually taller than the stock ones....235/70-16's are 29" tall, while 285/60-16's are 29.5" tall. So you have not changed your final drive ratio with the new tires.

If most of your driving is around town, as you have indicated, then 4.10's will give you a serious upgrade in off-the-line oomph, with a minimum hit in mileage. You may even gain some in the mileage department.

 

Thanks for all the input guys....

 

I would go 4.10's, mileage will not differ very much at all from 3.90's. I would definetly go 4.10's though for that little extra gear and besides you are in town all the time. I have run 4.10's with 27 inch tires and it wasn't too much for me. You make the call but you are only talking about a 100-200 rpm difference at 60 mph prob. between the 4.10's and 3.90's.

 

If you do alot of city driving then get the 4.10s if you do more highway get 3.73s i would just get a stall for more off the line acceleration.