2nd Gen Non-Engine/Transmission Tires for a 2wd 2500 235/255/285???

[bkroupa]

I'll be needing tires soon & I've searched through most of the tire post. I travel mostly on road & value long life, good mpg & value.

I have a 5spd & 4. 10's with the stock 6. 5" wide wheels. My mileage is good, but I'd like to reduce my cruising RPM some. It's roughly 2500 RPM at 70mph now. Discount tire recomends 285/75D's even on these skinney wheels (I have a source for Revo's $159 carry out), I was eyeballing 255/85D Cooper LT's, but they are not real common. 265/75 E's or 235/85E's would get me 4% RPM reduction. I'm not too worried about looks, the 245's look fine to me.

Any of these would work, the 255's or the 285's would make the most RPM difference. Any opinions or experiences welcome.

 

[ahansen]

I just purchased a set of 255/85's. I have the 5spd with the 4. 10. I like the 255's size better than the 235's I had before this. The 255's seem to ride better on the expressway. I was concerned with the extra height and towing ability with the 255's. But the bigger tire has not been a problem and I have not had a problem towing a 3 horse trailer.

 

[VicR]

I have heard that the 265/75's are as large as you can go on the 2wd w/o rubbing, but also heard an unconfirmed rumor that the 285's will fit. I will likely go to the 265's next time the 99 2wd needs tires as they are easily available in E.



Please post your results with whatever you end up doing. One other thought, if you have the mag-hytec rear end you might have clearance problems with the spare.



Good luck,



-Vic

 

[Ncostello]

I thought about this alot... then ended up with 245/75's after all. I had 235/85's which are basically the same height as 265/75's... just narrower by 30 mm. I got the Kumho KL41's all terrain. Great deal on a very very good tire. I'd put them up against any brand for quality, looks and traction. No road noise either.



I wanted the 265's... but the 6. 5" steel chrome wheels are too narrow for safety I think. I see folks putting 285's and even 315's on them in 4WD applications... but not for me.

 

[RKohn]

Definitely the 255's. 285's would feel loose and sloppy on 6. 5"s.

 

[VicR]

Did a little math using an old formula from a 4x4 mag. It says RPM=(MPH x drive ratio x 336)/ tire diameter (which I got from http://www.1010tires.com/TireSizeCalculator.asp?action=submit)



So with my 99, I calculate that going to 255/85's would shave about 8% of the RPM's off at 70 MPH. This is based on my 3. 54 rear end and NV 5600 transmission. I'll probably only go to 265/75's though. While the RPM gain is only about 1/2 that of the 255's, I am more confident they will fit w/o rubbing and the spare will fit.



(sorry the table got a little screwed up and the columns don't line up)



-Vic



size rpm mph ratio constant tire dia %

245/75 2001. 053185 70 2. 5915 336 30. 46 100%

265/75 1926. 424779 70 2. 5915 336 31. 64 96%

255/85 1843. 680581 70 2. 5915 336 33. 06 92%

285/75 1856. 597015 70 2. 5915 336 32. 83 93%

 

[bkroupa]

So... do the 255's clear on a 2wd???

 

[bkroupa]

Update, I did install 285/75's on my 2wd using '01 alloy wheels. They fit great/look good on it. I did reduce my cruise RPM 10%(compared to the worn 245's, but the mpg improved very little (. 5 mpg)with the Geolander HT's I bought. I read consumer reports test & the Michelin LTX had much lower rolling resistance, but also had a worse rating on wet traction. The truck drives great with these, but new tires always feel better than old ones.

I like the change, but cant justify the cost with fuel mileage improvements.