johnr9q

My 99 dodge PU has stock 16" wheels and I would like to increase the diameter to clos the RPM down to improve fuel economy. Anyone have ideas on what wheels I should get??? thanks

derek840378

wheels really have nothing to do w/ lowering rpm's. you can have a 25" tire on a 20" wheel or 44" tire on 15" wheel. bigger wheels really only work if you have the same (numerically) sized tire. for instance, my truck has a 255/70-15 (29"), the other day i saw a truck w/ a 255/70-16 (30"). since his wheel was an inch taller, the circumference is 3.141... (pi)" bigger. therefore, if we had the same gears in the tranny and rearend, his engine would be running about 10 percent slower at any given speed. but if your really just looking for a larger wheel, you cant go wrong w/ a set of 3rd gens
hope this wasnt too confusing

johnr9q

Derek: Thanks for the response. I realize that just the larger rim won't give me more circumference around the perimeter of the time but I am afraid that if I put a larger diameter tire on my existing rim to slow down my RPM I won't gain much due to loses in more rolling resistance (probably more tread on the road and more bulk in the tire to flex which adds resistance), more bulk and weight which requires more fuel to turn etc. I have observed vehicles that are designed to go very fast (Like 500 mph on the Bonneville Salt Flats) and vehicles that are designed to get outrageous fuel economy and in both these situations the wheels are very large and the tires very small and skinny. I remember as a kid my first bike was a fat tire bike and when I finally got a racing bike (with skinny tires) I couldn't believe how much faster I could go. I think you get the idea......So I want a larger diameter rim and a smaller tire and hopefully the combination would get me in the 33 1/2 inch diameter range. (currently 29.5inch) Also I need to maintain my requirement for load range "E" What size wheel does the 3rd Generation have?

BlackSunShyne

Third Gens come with a 17" wheel. I hope to be removing mine for some after market wheels and tires/lift kit in a few months.

derek840378

i get what you're saying. 2 tires with the same diameter will typically get better milage w/ a larger wheel. the more sidewall, the "mooshier" the tire, the more it conforms to the road, and the more drag it creates. a 3rd gen wheel is 17". a tire that size (33") for a 17" wheel would most likely be an off-road tire. if you want 33" on a street tire you may need to step up to about a 20 or 22" wheel, but finding an E rated tire that size may be hard to find. your best bet may be to run 19.5 supersingles

gman07

Also consider the increase in rotational mass of the larger wheel. Going from 16" to 19.5" adds a lot of metal to be turned.

derek840378

alcoa and similar companies make nice aluminum ss's

gman07

Good point, aluminum wheels would help.

OutlawStorm

http://www.miata.net/garage/tirecalc.html


there is a lil thing to see what different size tires will do for you

atc250r

I just put a set of 20" American Racing aluminum wheels on mine a few months ago. They are not "bling wheels" at all but simply a larger version of the AR Baja wheels. For now I am running 275/55/20's Goodyear Eagle LS's on it but once I square away some other maintenance and save up some money I'll be going to something much bigger along with a small lift. These are the teflon coated version:



I got the polished aluminum ones though.

John

derek840378

thats a 32" tire, pretty close to what johnr9q was looking for but i doubt they're E rated

atc250r

You're absolutely right, they're not but they did come off of a Chevy SS pickup so they have to be somewhat durable with a fairly heavy vehicle. I don't pull very heavy with my truck, the most I pull is my boat or my car which are both under 8,000lbs with their trailer. Kumho has come out with some fairly reasonable tires in similar sizes that are "D" rated:



The second one from the bottom is 33.9" tall so it'll fit with just a leveling kit. I'm debating that or the Nitto Terra Grappler but those are considerably more expensive. The Kumho's are under $250 each from Tire Rack. If I didn't have to blow a bunch of money on the front end rebuild I could almost afford the Kumho's now.

John

Mglass1045

If you are lookin for big rims check out Rickson Wheels. They make some 19.5" rims. They have a forged aluminum rim that's 32lbs, but it's also just shy of $500. Not sure about low pro tires for them though. They do have wheel and tire combos.

atc250r

The AR ones are under $1000 for a set of 4.

http://cgi.ebay.com/ebaymotors/8-LUG...QQcmdZViewItem

Sorry for the long URL but I don't see a button here to make a shortcut for it.

John

HOHN

The difference between a 16" and 17" wheel isn't significant enough to justify the expense.

If you want tall and skinny with a larger wheel, then a 19.5" wheel and commercial rubber is what you want. Very low rolling resistance, BUT very heavy and huge increase in unsprung weight.

Such a setup with commercial rubber may gain MPG on the hwy (steady state), but certainly will COST mpg around town where you are having to speed up and slow down all that extra mass.

19.5" rubber is also in load ranges f-h (super tough) and the higher load tires have a brutally rough ride.....

jh