Just have to ask

Does anybody know what size or whatever type of space saver tire and rim assembly will work on my 2006 dodge dakota?Finally got the pieces together to repair the differential,looks like I’m going to have to keep it,this year its going on a diet and I probaly will install an electric fan for better mileage and a little better pickup(non ethanol gas makes a noticable difference in the mileage on this truck)-Kevin

You won’t save enough on mileage to offset the cost of the doughnut. I’m betting the same will be true of the fan, once you add in the cost of installing the temp sensor and relay to operate it.

The best you can do is to ensure it’s kept in as good an operating condition as possible and drive modestly.

Agree. The first time you have to use that donut 50 miles from no where will be the last. I would always use exact sized tires and not donuts, even if they were the same diameter and especially on the rear wheels. Besides, it is a truck and in theory, any weight you take out of the rear is worse, not better for handling and traction. .

Years ago we had a regular customer come in with mini spare on R/F and a repaired full size tire & wheel assembly in the trunk. Seems they had taken a trip to Fla from Pa & around NC the R/F went flat. The husband put the spare on & threw the flat in the trunk. First shop they got to they told the guy, “Fix my flat.” & that’s exactly what the tech did. Then he put the repaired tire back in the trunk, (having not actually been instructed to put the spare away, etc!)

After maybe 1300 miles the mini spare actually didn’t look too much the worse for wear.

Don’t do this with your car though!

True ,true-but I usually just repair the tire if possible.
,an increase of 1-2 mpg is not unheard of,its about the only way to get a little more out of these things.I’m hoping to get to the point were the truck will be semi retired(trash,Firewood and towing duty)was considering a set of alloy rims with smaller lighter all season tires for summer dry running,these new coopers really have the bite.
I had to plug a tire on my wifes civic the other day,it was leaking under the stud,dont really understand what happened,took the vise grips and pulled the stud out,reamed the hole and put a string plug in{holds air now}
Thanks fellows,youall are probaly right,I dont understand way everything doesnt utilize E-fans,did you realize the clutch fan on a semi can gobble up 50-75 HP?on these little guys more like 10-15 HP at cruise,doesnt seem right but I can notice the diferrence on something that doesnt have much power-Kevin

I agree. If you drive a mini at sane speeds you can get significant miles out of it. Try keeping up with highway traffic in the rain with it on the rear and have to make an emergency maneuver, and it will be “the last time” you use one…if you have a choice. It would be like buying something that wasn’t as good as I already have for little or no reason. That’s my point Kevin.

I think the warning to ‘only drive xx miles at xx MPH’ is mostly to prevent damage to the car’s differential due to high speed/long distance driving with different tire sizes on the driven axle, not because the donut spares are inherently prone to fast wear.

An increase of 1-2 mpg expectation for replacing your spare with a doughnut is unrealistic.
If you reduce the weight by 5 pounds in a 3,000 pound vehicle, that’s only a 1.6% (.0016)weight reduction. ten pounds would be 3.3% (.0033). In a vehicle getting 25mpg you should expect an increase of less than 1/10th of a mpg (1st case) or less than 2/10th of a mpg (2nd case).

The big savings for designers is in the improved ability to utilize space. That enables a usable vehicle of a smaller size with usable utility. That enables lower overall vehicle weight as well as improved aerodynamics. But to take a specific vehicle and change the spare out for a doughnut just isn’t worth the cost of the doughnut.

@ Same,I was referring to the E-fan,not the weight reduction caused by the space saver spare-Kevin

Surprisingly, one of the biggest savings can occur by improving the aerodynamics of your truck of which, 40% is the undercarriage. But, since trucks like yours are dedicated purpose vehicles, what good does it do to lower it or put on cladding underneath that could be easily damaged. You say you are seldom using it. So where is the pay back of doing anything at all ?

I have a truck and I would not think of altering anything about it. I suppose you could debadge it to help the “airflow” which is a silly thing I do all the time to all my cars. . Usually, we truck nuts add crappolla to increase it’s usability, like racks and front hitches and caps…which decreases mileage. A truck was never made to be an Eco car and trying to make one that way is going down a dark alley of total uncertainty. That’s been my experience in the eight trucks I have owned in the last forty years of driving them .

Be happy compadre. The price of gas now doesn’t make any investment worth it in this area other then, keeping the tires pumped up a little harder then normal and driving really conservatively…just bubble along in the highest of gears possible. That will save the most for now. You actually save most long term by keeping it on he road as long as possible.

I agree about keeping it now,but I have to drive the heck out of the thing a trip to VA Beach was costing over 80$( and a lot cheaper now),hopefully when the weather improves,work will start again and I can get something more economical,hard to get a job with what the state saddled Me with-Kevin

If you reduce the weight by 5 pounds in a 3,000 pound vehicle, that’s only a 1.6% (.0016)weight reduction. ten pounds would be 3.3% (.0033).

0.16% and 0.33% respectively… you had the decimal part right but slipped a decimal point in the percentage, no?

5 or 10 pounds reduction will have literally NO noticeable effect on gas mileage…

It’s true, TT, I did. Nice catch. Can I plead old age??? {:stuck_out_tongue:

I only noticed it because I was curious how you correlated weight reduction to fuel savings. The percentage weight reduction didn’t pass the initial sniff test…I’ve messed around with fuel consumption versus weight before although it wasn’t automotive related. There are all kinds of compounding factors that don’t make for a straight line fit so I was curious when I saw you had actual numbers…

All true, but the biggest factor with going to a doughnut would be the weight reduction, and it was enough to make my point… all moot, as it turns out.