Quote:
Originally Posted by lasitter
1996 Ford F-150 4.9L (Straight Six) with many modifications ...
The current tires are 108T, but going down to 106 would represent the loss of 89 pounds of capacity per tire. I'd much rather go the other way though. .....
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OK so that eliminates everything lower than a 108 Load Index.
Quote:
Originally Posted by lasitter
........ Oh yes. If I can improve my fuel economy via this experiment, it will entirely worth it in terms of entertainment value. ....
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This was the response to the cost of wheel question. That gets us down to this list:
General Tire Grabber HTS LRR 235/75 R15 109T XL 2271 lbs./51psi 12.0/32" 32lbs 7.2"
Michelin Latitude Tour HP LRR 255/65 R16 109H SL 2271 lbs./51psi 10.5/32" 33lbs 8.5" (owners hated it)
General Tire Grabber UHP --- 255/65 R16 109H SL 2271 lbs./51psi 12.0/32" 34lbs 7.7"
General Tire Grabber UHP --- 255/55ZR18 109W XL 2271 lbs./51psi 11.0/32" 32lbs 8.5"
Pirelli Scorpion Verde AS LRR 255/55 R18 109V XL 2271 lbs./50psi 11.0/12" 36lbs 9.0"
Continental CrossContact LX20 LRR 255/55 R18 109H XL 2271 lbs./51psi 12.0/32" 35lbs 8.6"
I would eliminate the anything with a higher than T speed rating - extra cap plies means higher RR.
That leaves only the 235/75R15 General Grabber HTS.
Now your current Kumho Solus KR21's are so very similar to the General Grabber HTS's, I don't think you will experience any improvement in fuel economy. In fact, if you make this change, you will start off WORSE, and it will gradually get back to where you are now - worn tires.
The only thing I can suggest is to go larger - P265/75R15. There MIGHT be fitment issues, and the improvement is small - 1% or 2%. Personally, I don't think this is worth the risk.