Tires 225/75R16 To a 295/75R16

[LJ-TJ]

So presently I have a set of 225/75R16's on my 1975 21 footer Brave. She runs at about 23/2400 rpm at cruse around 50mph. I was thinking of going to a taller tire say a 295/75R16 to bring the rpm down.  i?? maybe improve the milage a bit but that's not the main reason. Do you think she might be a little swayiee in the side walls and bum end rolling down the highway. Do yeah think they'll fit in the wheel wells? Open for two cents worth. D:oH!

[Elandan2]

I think that 295's would be way too wide for the duals.

[Rickf1985]

A taller tire would be a 235/85-16, Very popular tire and used on damn near every pickup from the 80's through the 2000's. The second number is where you get your height. 85% as high as it is wide. The tires you mentioned would be about the same height but way to wide for duals, they would be touching and that is very bad. According to my tired math you would gain approximately 32mm in height, 64mm rolling diameter with the 235's. Remember, any gain in tire size will be a loss in power, not much but you will notice it on the steeper hills and maybe in the mileage. You are right dead square in the power band where you are at now.

[LJ-TJ]

Good stuff Rick I wasn't sure how all this worked. I was looking for a way to get a taller tire in order to drop my RPM with out buying new rims. At one time I had considered going to  the 19's every bodies talking about.

[Rickf1985]

You do not want to drop you rpm's all across the board or you will pay the price in the hills. If you want to get lower rpms for the flat ground it is better to get an overdrive unit. That way you have the option of getting your lower gearing back if you need it. Plus you will get lower rpms than you would with tires.

[LJ-TJ]

Yeah I here yeah. I was just looking for an inexpensive way to cruse the interstate so she didn't sound like she was in over  speed all the time Hm?

[legomybago]

My 440 runs about 3,000-3,100 rpms @ 60 mph. Eat that fuel hunny.....On steep hill climbs, I run 2nd gear, around 45 mph, somewhere near 3,600-3,800 rpms...The 440 is a great boat motor!

[LJ-TJ]

Well in that case I'm in the ball game

[Rickf1985]

Yea, well, I don't thing I would be pushing 3800 too much!
Here is something for you to dwell on Lego, At 3800 rpm the piston is going up and down 63 times a SECOND! That piston weighs about 1 1/2 pounds. Picture how much force is involved in making that piston change direction at that speed! And the connecting rod weighs about 3-4 lbs.!!!