jballou

I have the toyo 35's in the 18 rim and would like to have a little higher rpm's. I am at 1350 with OD at 55 and the truck seems to lug with towing. If it is in tow/haul it seems to be about 1850. I would like to tow the toyhauler at 65 or so without the rpm's so high in tow/haul so I put it in OD to lower the rpm's and it lugs on the hills.

Basicily I am looking for a tire that would add 200 or 250 rpm's to make the engine in the sweet spot with OD and not lugging it, a little less smokey on the hills. Would the 33 by toyo give me what I am looking for?

SundayMoney

I don't think the 33s would be enough.

When I went from 265s to 285s (about like going from 33s to 35s) I only lost 150rpms.

You might gain 200 dropping down 2" in tire size.

By the way, whats the reasoning for not wanting to run the higher rpms?

If its wear on the engine,don't worry about it. In some applications the Cummins is rated to run at 3000 rpms 24/7.

schaef_12

I'd say mileage is his reasoning with $4 diesel.

bigwheels94

I've found the 285's are the best compromise for towing/streeting. I'm @ 1500 @ 50mph. in OD just over 2000rpm @ 75 in OD. I can still drop into 3rd, & be @ 2850rpm.

BioJoe

285 is the width of the tire in mm's not the overall diameter of the tire. It won't make a difference if you have 285's or 265's unless you also change the next number which is the ratio of sidewall height to tire width in percent. You need both numbers to figure out how big the tire is in diameter. A 285/75 is about 28mm taller than a 285/65. Go to http://www.4lo.com/4LoCalc.htm and there you'll find plenty of calculators to get you where you need to be.

1-2-3

Smaller diameter tires or lower gears. What gear ratio do you have now? Rim size dosen't matter. It's the outside diameter of the tire that counts. Width will matter a tiny fraction. A little more rolling resistance. Might not be measurable.

j-fox

There are times when I wish our OD ratio was .85 or even .8 as that narrows the spread between 3 and 4.

renopker

How would the od ratio change the 3-4 split?

jkitterman

You are geared about right if you are at 2150-2250 @ 65 mph. This is from Cummins QuickSpec on their website. You also should be above 1900 but you seem so close at 1850 you quoted. Just stick with the tow/haul

stumpjumper

on that 2004.5 and you push the tow haul it disables o/d. i have the 285/70/17 bfg a/t and it's perfect on the rpm. on model year 05 tow/haul engaged it will still go into o/d.

jballou

When I got my truck it had the 35's on it so I never got to see what it was like with towing and the stock rpm's. I am guessing that at 55 it would have been about 1650 or 1700 at 55 mph. In my situation for mpg the truck seems to be more rpm dependant than speed vs wind resistance. I either drive to fast for towing and get better mileage or use more fuel and slower. Tough delema huh?

It seems with the tow haul activated I get 1.5 mpg less due to the higher rpm's. Between the od selected and the tow haul on there is a large gap of rpm's that I would like or need to be in. Make sense?

I mentioned the 18 rims due to the lack of exact tire size choices. would like to try the nitto dura grappler tires.. Any users?

Got the 3.73 gears.

Looks like I am making a bigger issue of it than it really is.

Is there a update for the OD tow haul programming on the 04.5's? Would that help my issue?

mcoleman

Actually yes it will. Using the BFG's for instance the 265-75 is 31.7 inches tall whereas the 285-75 is 32.8 inches tall. That equates to 22 rotations per mile difference. A 245-75 is only 30.5 inches tall.

AH64ID

There are standard tire sizes... when some says 245, 265, 285 we know what they are saying... wether it be 245/75/16 or 245/70/17... they are about the same... same as 265/75/16 or 265/70/17, and 285/70/17.... So yes it will make a difference... we all talk in standard sizes... which is why when people say 285/75/17 they say it all, its a non standard size.

mj007

Final Drive Info (rpm vs speed): MPH = Tire Dia. x RPM x Trans. Ratio DIVIDED BY: 336 x Final Drive Ratio

ellerman

It wouldn't be that cheap but I would put 4:10's in. I think the trucks look so much better with a 35" tire that is worth it. Also, you may want to look at the load rating of your 35's vs. 33's that you are considering. The Toyo MT's have a pretty awesome load rating in the 35" size but I'm not sure about the 33's. Eric