Tires/Gear Ratio/MPG

[mcrews]

to answer the first post. I would NOT go w/ a smaller diameter tire.
roy, He would increwase his mileage with the taller tire.

[Frank Lee]

When I first put my '59 Bel Air back on the road after a 33 year hiatus, I borrowed the wheels and tires from my Corvair. They bolted right up but were 10-15% undersize as far as outside diameter IIRC. I can say that WOW, throttle response from the 283/powerglide combo was MUCH enhanced! (The lowness looked pretty cool too!) I subsequently fitted tires that were oversized, effectively killing vigorous throttle response in exchange for a nice, easy, low rpm cruise.

So if OP wants an affordable, easily reversible "gear down" for towing power I would sure think it would work.

[Dcarver]

The tires I will be looking into will be LT tires for sure. Found out they are of course the best for towing.
I do not tow at my max load so I'd be ok with going slightly smaller and I feel the LTs will be better than the standard P rated tires I have now
I don't think the smaller tired will give me worse mpg however. Wouldn't my speedometer be off so by driving 65 on the speedometer would actually be 70mph this meaning my Rpms are lower and increasing the gas mileage?

[Frank Lee]

Now yer all bass-ackwards.

[royanddoreen]

lots of info on this site about this topic just use the search top of the page dcarver.

[Sporty Modder]

A tires load cap is not necassarily reduced by going narrower. I have a set of 235 tires with a higher load cap than the 265s currently on my truck, what matters in lt tires is load rating, some differant ratings are C,D,&E.

[mcrews]

Let's speak clearly here.
1. smaller diameter THAN STOCK (this is important because a smalll tire than what is currently on the vehicle MAY NOT be the stock size) will produce higher rpms and worse mileage.
2. A larger diameter than stock will produce a lower rpm thus better mileage.
IGNORE the speedometer/odometer.
I use a gps set on meters instead of miles to to calibrate my Scangauge. (setting to meters gives a more exact measurement to set by.) I then change back to miles.
Once I have the gps and scangauge giving me a precise mph reading I tend to ignore the speedo.

IF you want more tourgue to tow then smaller diameter MIGHT achieve that, given load wieghts. But a smaller tire will not....in general produce better mpg.

[gone-ot]

...the over/under-sizing of tires/rims has the same effect as changing the axle-ratio!