Rotational weight increase... (1 Viewer)

[gregnash]

So this year I will be replacing the mismatched tires on my 1985 FJ60 with something much nicer. Truck is completely stock with no mods other than a desmog and new head unit. She has less than 200k on her and still pulls pretty strong.

The question is, I want to up to 31" tires and have narrowed it down to pretty much either the Cooper Discoverer AT3 or the Cooper Discoverer S/T Maxx (both offered in the 31x10.5x15).

The question is that the S/T Maxx is an increase of 4lbs per tire not to mention the resistance of going from the AT of the AT3 to a more "Extreme Terrain) of the S/T Maxx (not quite a MT but not an AT).

With all the said, am I going to see a huge decrease in mileage and addition wear/tear on the engine/drivetrain with the S/T Maxx? I really like both, but have fallen in love with the aesthetics of the S/T Maxx and both have gotten exceptional reviews for what I will do with them (mild off-roading, truck will be an Expedition rig at some point in its life but not a crawler).

 

[Bama4door]

4lbs a tire is nothing IMO

 

[mcgaskins]

I think it's very difficult to notice until you get to around 10 lbs per tire increase unless you're working a sports car or motorcycle!

 

[gregnash]

Ok thanks guys.. that is basically what I figured but I wanted to be sure that if I did decide to go with the S/T Maxx I was not going to see a huge increase in rotational inertia and resistance which would then cause issues with the engine/drivetrain. Excited I love the look of these tires!! And so glad that they have decided to release new sizes (three different 15" sizes).

 

[73fj40lc]

I have the ST Maxx tires in a 285/75/16. You will love them. I don't have any complaints. I haven't noticed any difference in power from my last set of tires which were Mickey Thompson's in the same size. I have had my set for about a year now and my brother has had a set on his Tacoma for about 2 years. He still is impressed with them. I let him do the testing for me before I bought my set. There are great reviews on the tires but as you mentioned one complaint was the wieght. I don't mind the extra wieght as the tire is designed to last and be very rugged in all conditions.

 

[GeologistFelix]

I went from 235 street tires to 32" swampers in my 60, and actually saw an increase in highway mileage, from 12.5 average/13 max to 14 average/15 max.

There are several factors in play, here, though:

1. The bigger tire means you go (new diameter / old diameter) times further per rotation of the tires, so your odometer and speedo will read low by that ratio, meaning better mpg than simple miles-on-trip-odometer / gallons-to-top-off.

2. Lower rpms for the same speed means that an old tractor engine that had gears chosen for a time when the maximum national speed limit was 55 will be happier at highway speeds.

3. Numerically lower final drive ratio (and more rotating weight on a larger diameter) will mean more sluggish starts from stops, and probably somewhat worse city mileage. I went from a fairly solid 12 city to about 10-11 depending on traffic, but I don't commute in the cruiser so I don't really care about that.