cbr600rx7

I am trying to figure out whats going on with my truck i read a lot from members about running higher gears when going to bigger tires. My truck has 35 MT's and i can say she still moves pretty good. I can hold speed in 5th gear driving up a few good hills on the way to work and dont find my self down shifting too much. I also had a chance to drive a friends truck with almost 80,000 less miles then my truck. He also has a intake and full exhaust with no cat. My truck still has a cat and factory toyota muffler but pulls a lot harder. I had to really get his truck up in RPM's just to get it up in speed and 5th gear was useless (could hardly hold 55 mph on flat ground) I am guessing his truck tips the scales a good 200lbs lighter then mine since he doesn't have the roll bar, tow hitch, or spare tire that i have on my truck and with the intake and exhaust i am sure he is picking up a few ponies so i dont know what the deal is. Both trucks are running 35 inch tires, both 5 speeds, and both have 4.10 gears.

My truck is by no means any thing special. She is only running 4.10 gears, the stock fan, ac, and ps. The engine was refreshed about 9000 miles ago so i am guessing that might have a hole lot to do with it but still. Seems a little strange.

BoredOutnJackdUp

lower gears going to bigger tires***

Yeah your motor is probably just healthier

are you positive your truck has 410s?
and the kind of tire makes a big difference.

i had 35x12.5s bfg m/ts on my 83 w/ 410s and it wasnt bad.
But got 35x14.5 boggers and could barely hit 55.

It really could be quite a few things.

Duke70

I'm running a 93 22re in my 84 with 35s and still have the stock 4.10s in it and it does fine but I do have to drop back into 4th on hills, When in 5th at 55 to 60 I'm only turning like 1200rpm's , But 5.29s would be alot better

snobdds

Yea too many variables to even try and compare two trucks.

sbhern89

I got a 6" lift w 35 x 12.5 m/t bfgoodrich on my 85 pickup efi . I run on 410 as well and I can get 75 mph and no prob

snobdds

Down hill dosen't count

tj884Rdlx

x2 on this.

air/fuel mix and timing really affect "driveability" and "seat-of-the-pants-dyno" measurements.

my experience - i ran 31s for a while, then went up to 33s with my factory 4.1s for about a year.

when i finally got my 4.88s installed, i expected this huge improvement in acceleration. it really wasn't there, and i was disappointed.

i took it to shop for some engine diagnosis, and they tuned the timing using more than just the markings available on the motor. their tweaking brought out a LOT more power, and when i drove it home it had that improvement in acceleration i was expecting from the gear swap.

so there's definitely a lot of variables to make comparing two trucks difficult to get "apples to apples". you can't just pin it on the tires.

ideally, you'd have to borrow a set of stock size tires, put them on each truck and do a dyno run. get the trucks tuned to matching performance using identical tire sets, THEN compare the effect that different tires has on the trucks, out on the street.

that's ideal of course. not too practical.