Changing Tire Size?
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Changing Tire Size?
My 1999 F350-SD-CC-V10-4:30 axle-2wd dually came with 215/85R16 tires.
I want to go up to 235/85R16. I tow a 10K fifth wheel maybe 30% of the time. Will there be a clearance problem on the duals-- ie will they rub together?
What are the pros and cons?
I am not doing this for better mileage, but it seems like there would be a slight increase due to the effective reduction of the axle ratio and lower RPM. But previous posts say there will be a decrease. Why a decrease?
Thanks to all for your help.
I want to go up to 235/85R16. I tow a 10K fifth wheel maybe 30% of the time. Will there be a clearance problem on the duals-- ie will they rub together?
What are the pros and cons?
I am not doing this for better mileage, but it seems like there would be a slight increase due to the effective reduction of the axle ratio and lower RPM. But previous posts say there will be a decrease. Why a decrease?
Thanks to all for your help.
Elder User
Joined: Dec 2005
Posts: 703
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From: Middle of a field CT
I'm not too familiar with DRW's but I do know if they rub your in for disaster the haet from them rubbibg will cause a blowout. Changing tire size won't really affect milage that much, at least not so that you notice. Interesting fact: Running 285 75 r16's on a srw truck actually corrects the speddometer. Ford set it about 2mph fast to keep us in line I suppose.
EDIT: Some see decreased milage because more tire = more rotational mass so it takes more energy to get and keep those bigger tires spinning
EDIT: Some see decreased milage because more tire = more rotational mass so it takes more energy to get and keep those bigger tires spinning
Postmaster
Joined: Aug 2006
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'99 DRW 4X4's came out of the factory with 235/85R16's, same as I had on my '00 DRW and you don't have to worry about them rubbing. Plenty of room.
Your city economy may decrease a little, but on the highway it should be a little better as your cruzing RPM's should be about 100 RPM lower and your effective gear ratio would be about a 4.10. Your change in tire height is minimal, only about 4%.
Your city economy may decrease a little, but on the highway it should be a little better as your cruzing RPM's should be about 100 RPM lower and your effective gear ratio would be about a 4.10. Your change in tire height is minimal, only about 4%.
Postmaster
Joined: Aug 2006
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If you have not decided on a tire yet, make sure you check out Michelin LTX M/S, Michelin LTX A/S and Michelin LTX A/T. I had over 70,000 on my Michelin LTX A/T's when I traded it in, and they still had tread on them. That was impressive considering I got less then 40,000 out of the stock Generals.
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Thanks, I'm glad you brought up tire type. I have looked at the LTX's and heard good things, but am having trouble justifying the extra $50-$60 per tire (times 6) over the BFG Commercial TA's I have now. They have 50000 miles with tread remaining, but are starting to have balancing problems. The LTX's might dry out before I wore them out.
Are they worth the extra $$$$$?
Are they worth the extra $$$$$?
Postmaster
Joined: Aug 2006
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Were they worth the extra $$$, for me yes. In 70,000+ miles I rotated them every 7,500 mi, never had to rebalance, never a flat, never even picked up a nail for that matter. Plus in 4 years and almost 120,000 mi, it was the only set of tires I had to buy.
Granted I never looked at BFG at the time. I can not complain about them either. As BFG is Michelin.
Granted I never looked at BFG at the time. I can not complain about them either. As BFG is Michelin.
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Post Fiend
Joined: Aug 2002
Posts: 17,334
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From: PA
As for your tire size change, go to www.1010tire.com/TireSizeCalculator.asp?... for safe size changes. Thanks to someone else on this FTE site, I was able to check to make sure I made the right decision on upgrade. I personally like the Cooper Discover ATR's on my SD250. Good Luck!
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