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Tires/tire downsize over gear change


QUESTION: Seeking your thoughts on all factors to consider here.  I have a 99 F250 Superduty 4x4 SRW with 3.73 gear ratio...and seeking to increase that ratio (and repace worn tires) safely, for a lower cost than swapping to 4.10's (x2).

Stock lariot package wheels are 16x7 AL with 265/75/16E (123/120) and 31.5in circumference.  Seeking the smallest load rane E tire that fits my wheel and find two choices: 245/75/16E (120/116)@ 1in smaller, and 225/75/16E (115/112) rating @ 2in smaller.

Any saftey concerns with reducing the overall vehicle width one inch with the 225's?  They are 7.1in wide, down from 8.1in on the 265's.  I could use a small hubcentric wheel spacers to bump out the stock wheels 1/4 per side and cut the effect in half?

Thanks in advance,


Do you remember the Ford / Firestone thing a few years ago?  The discussion about inflation pressure was really about load carrying capacity - and the lesson from that experience was that Ford had not done a good job of selecting the load carrying capacity of their tires.  Yes, Firestone was the major culprit, but the situation revealed many side issues.

So I am not a fan of going DOWN in load carrying capacity - and that's where you are trying go.  I therefore have HUGE (!!!!) safety concerns.

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QUESTION: I'm not sure that applies here, all three tire sizes we are discussing are 80psi, load range E tires.  I haven't heard of many load range E tire failures?

And also the 245/75/16 was a stock tire option, so it must be acceptable option.  I do find a General Grabber HTS in this size is 30in around...1 1/2 less than my current tire.  Only it and the Michelin M/S2 are classified as Low Rolling Resistance...can you speak to this category, of is it just marketing bs?

Thanks again!


Not many people heard about the Firestone failures until it hit the news.  

I did a little research and found that, at the time, the failure rate of the Firestones was less than 1/2%.  Nowadays, the failure rate is lower than that, but I can guarantee that there are Load Range E failures - albeit at a lower rate.

Besides, look at what is currently available from Ford.  The tire sizes are all larger than the ones you mentioned.

You asked for my opinion and that is what it is.  I don't think this is a good idea.   - And I think the biggest problem is that tire failures sometimes result in fatalities.  I really don't want you to be part of that statistic.

LRR?  First you have to understand that this is a relative term.  It means better rolling resistance compared to comparable tires (tires of the same treadwear and traction characteristics.  

It does NOT mean the rolling resistance is low in the absolute sense.  To get a low RR, treadwear and/or traction has to be sacrificed - something most people don't want.  

So I wouldn't expect these tires to give better fuel economy to anything currently available, but I would expect them to be better than tires in the same category.  


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Barry Smith


I have over 30 years experience in the design, manufacturing, and testing of tires. I have served as the technical advisor to the "800" number. I have authored or co-authored many publications - usually without credit. I can answer almost any technical question, but please don`t ask me to compare brands. I probably have prejudices because of my work experience.


Member SAE (Society of Automotive Engineers) Member Tire Society (Tire Technical Organization) SCCA Regional Competiton License holder Authored many training manuals on tires, their care and use.

SAE (Society of Automotive Engineers) SCCA (Sports Car Club of America) Tire Society

You may want to visit my web site:

I am a graduate of the University of Dayton, Dayton, OH - BME, 1971 I attended graduate school at the University of Akron - but did not complete my PhD - something I regret.

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