Will taller tires or wheels help MPG on the 90 lude??
Hello, Just wondering if I went to either taller tires or maybe 15" wheels and the stock size tire, but 15", instead of the stock 14"s, if that would help on mpg? These 90 preludes are pretty low geared for the 70 mph freeway speeds, and I wonder how much that is effecting gas milage? I've been making it a point to try and keep it at or near 70 so as to not eat it so fast, but I definitely am one of the traffic flow impediments at that speed. My old 85 RX7 wasn't as quick, do to the different gearing, but the 140 mph mark on the speedometer definitely was for more than show. It loved to cruise the back hiways at 85, not that I would do that beings that the speed limit was only 50-55.
Thank you.
Well first you don't measure tires like that. It's rims that come in 15" or 16" or whatever. That's the inside diameter of the tire which also has zero impact on it's height. But to answer your question, it actually lowers your mpg to increase tire size. Your increasing rotational mass and weight, that means more power (gas) is required just to get them rolling. That's the easy/short answer, hope that helps.
Well first you don't measure tires like that. It's rims that come in 15" or 16" or whatever. That's the inside diameter of the tire which also has zero impact on it's height. But to answer your question, it actually lowers your mpg to increase tire size. Your increasing rotational mass and weight, that means more power (gas) is required just to get them rolling. That's the easy/short answer, hope that helps.
Yes you are right about not measuring tires like that. Maybe I should have been a little more clear about how I stated that. OK here I go. If one had stock tires that were 195/60/14" on steel 14" wheels, and wanted to increase the total physical height of his tire wheel combo by 1", which would be potentially lighter in weight (A) 195/60/15" tire on a 15" steel wheel? or (B) 195/60/15" tire on a 15" aluminum alloy wheel? or (C) an actual physically taller than stock by 1" ???/??/14" tire on a 14" steel wheel? or (D) an actual physically taller than stock by 1" ???/??/14" tire on a 14" aluminum alloy wheel?
The goal being to not exceed the weight of the stock wheel and tire combination by anymore than one has to while increasing physical tire and wheel combination height by 1" so as to be able to maintain lower engine RPMs at Interstate highway speeds. All this in the hope of achieving better fuel economy over all for someone who drives a 50/50 split between interstate and city driving.
I just know it will throw off yer speedometer, it will also make gear ratios seem different a lil bit, but it might make some difference in mileage by lowering rpm's on the freeway too at same time.
Yes you are right it will throw off the ol speedometer. By how much I'm not sure. Sure would have been nice if these 80s & early 90s preludes had one more gear.
What you're talking about is "rolling radius". Pretty much if you increase the rolling radius at all you are lowering your mpg. You can increase rim size and compensate for the increase by getting lo-pros(low profile tires). Provided you don't get an extremly heavy rim, you decrease rotational mass and weight, retain stock rolling radius so it doesn't throw the speedo off, and lo-pros have much lower forward rolling resistance so their even EASIER to roll than the stock tires. If you do that then you increase mpg, and effective (usable) HP to the wheels!
Last edited by xtreemjedi : 07-15-2008 at 06:15 PM.
What you're talking about is "rolling radius". Pretty much if you increase the rolling radius at all you are lowering your mpg. You can increase rim size and compensate for the increase by getting lo-pros(low profile tires). Provided you don't get an extremly heavy rim, you decrease rotational mass and weight, retain stock rolling radius so it doesn't throw the speedo off, and lo-pros have much lower forward rolling resistance so their even EASIER to roll than the stock tires. If you do that then you increase mpg, and effective (usable) HP to the wheels!
Bummer!, I guess there is no way around it without trading away for a bumpier hard on the rig tires, while still turning gas guzzling high rpms. I guess getting rid of this outdated 55er and getting something that is made to cruise at the current interstate speeds, and get better mpg is the way to go.
Thank you!
AutoForums.com is the premier network of enthusiast-owned
enthusiast-operated automotive communities.
We operate more than 100 automotive forums where our users consult peers for shopping information and advice, and share
experiences and opinions as a community.
Linear Mode
