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Discussion Starter · #1 · (Edited by Moderator)
just for giggles i shoe-horned my old honda accord rims and tires on the G1 today. they are some cheapo dual lug pattern rims i found on marketplace and they measure 16x7, they are wrapped with 205/50-16 firestones. from what i see this is about as big and wide as you can go with rear skirts without additional mods. 1.6" taller, 1.6" wider, .2" less sidewall, 5.1" more circumference, 61 less revs per mile. the rears clear the swing arm by a 1/4". when reinstalled the skirt, the rear most sidewall tickled it. 2 tugs on the aluminum mounting flange gave me a 1/4" gap on the spat/sidewall.

I road tested it on some washboard/pothole gravel roads and the ugliest tar road around here. made sure to go full bump several times even while cornering to try and get some rub and nothin, nada, all bueno. i should mention my car has stock springs and and all the weight of the ima and spare tire plus 40 pounds of random junk in the trunk plus 170 pounds of driver and 95 pounds of copilot test dog in the passenger seat. i do have very weak shocks and struts with 240k on the car and they look original spec, most roads in northern minnesota are horrible with our freeze/thaw cycles.

My car falls into the very uncomfortable to drive scenario with bad shocks, bad roads and repeated jack hammering on the spine. i prolly look hazardous to other traffic because of constantly dodging small road features that a typical sedan would laugh at. the big tire setup made a night and day difference on the ride quality. one big take away is the stupid number on the dash. i will have to figure my mpg by hand at the pump like the good old days. using my gps, the speedo/odo is 7.5% under actual, i cross referenced with an online tire size calculator and it says the discrepency is 7.6% basically spot on if you factor *10k/mi. of treadwear.

My stock tires weighed 88 pounds, new ones weigh 134 pounds. first gear feels correct in my opinion now, where before was too short feeling, second gear gets me up to our state speed limit and 4th feels like 5th did. i prolly wont need 5th near as often with 7.5% gain in gearing, id like to figure out if 4th gear assist can be disabled as it lands in an awkward spot now. i also lost some low limit regen on decel, which is unfortunate with all the stop and go in my area but all in all this mod helps me enjoy my ride now. i'll upload pics when i get better signal and i will update other side effects and opinions as they arise.
 

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Discussion Starter · #5 ·
Are you still able to get into lean burn with those? I was having a hard time when I had those size wheels on mine.
on county roads with a 55mph speed limit i can lean burn 4th gear at approx 58 to 60 mph. im gunna run down to the big city tonight and see what it does at higher highway speeds. i'll add that i have only had this car for about 3000 miles now. the lifetime mpg on the dash is 53.7, my personal average for the first oil change was 54.9. i'll be doing a 2.5 hour drive tonight and i will update some new mpg figures. i plan on topping off at the beginning and end of the trip and hand calculating the numbers.
 

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Discussion Starter · #7 ·
disclaimer: this post is full of math and is based on a very short 100mi test run

did my first mpg test run with the big tires today. unfortunately, the outside temp went from 60F when i installed them yesterday back down to 28F today for my maiden voyage, my ima needs a grid charge topoff, the first 40 miles had regen. nevertheless i just drove 100.0 gps miles anyways. my dash trip miles came to 94.7. that means my dash reads 5.3% below actual. my dash trip mpg was at 50.8. when i add the 5.3% to my dash i come up with 53.5 theoretical actual average mpg. my previous 3,000 miles with oem tires i was averaging 54.9. so far with less than desirable circumstances i have dropped my average by 1.4mpg. the difference could have a lot to do with all the regen, time will tell. i wont be driving the car again until friday night because i have a company work van to use for the rest of the week. I am familiar with calculating mpg with oversize tires from the old lifted pickups ive owned in the past. it is usually negligible at highway cruising because the larger diameter "adds to the gear ratio". where you will suffer with mpg is accelerating repeatedly, luckily our little cars have a very short first gear to help with this. i cant wait to burn through the first tank to get an accurate fill up measurement. the car rides so much nicer now. i had 50 psi in the oem tires and i ran with 40 psi in the monster tires today but it felt like i was driving on a cloud, road noise was peaceful and the heavier tires are more grounded, it doesnt death rattle over every crack in the street, all around smoother and quieter. i may actually invest more into this vehicle as time goes on.
i just projected the dollar to mile that this luxury upgrade cost me, 0.18 cents per mile at 3.80/gallon, in today's market where i live. that's 18 cents per hundred miles, $1.80 per 1,000mi., $18.00 per 10,000mi., $72.00 per 40,000mi.
i get tires for cost through my friends business and i mount and balance myself for no cost, so it definitely makes sense for me to roll the monster tires on my g1. the firestones i have are leftovers from previous vehicle i owned, however i can get them for 20 dollars less than i can get the potenza re92. you see where this is going. the offset in tire price is more than fuel price per mile saved. a set of potenzas would cost me $85 after tax more than the big tires but they would only save me $72 in fuel over an estimated 40,000 mile tread life.
All in all the mpg downgrade equals a ride quality upgrade that saves me 13 dollars in tire costs over the life of the tires. spend that 13 dollars back at the pump and i get 192 frequent flyer miles lol
not to mention: the new tires would out endure the o.e. ones anyways, less revs per mile and the extra surface area to wear off... i could go on and on but i'll save some for later.
 

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Discussion Starter · #9 · (Edited)
Part NumberSizeBP 1BP 2FinishBoreOffsetBSM (in)Rating (lb)Weight (lb)
426H6703GM3816X74x1004x4.5Gunmetal73.10385.500180021
heres the info i copy/pasted off the website, the margins dont line up vertically. i found them used on marketplace for 150 bucks. the tires are kinda midgrade, i think my cost was 80 each but that was a couple years ago
Tire Wheel Vehicle Car Automotive tire

here is more of a close up, 205/50-16, rim is 16 x 7, i cant fit my finger tip between inner sidewall and trailing arm, same goes for the fronts between the sidewall and the struts. the back of the skirts had zero clearance so i grabbed the rear bumper and bent it out till it matched the other gaps.
 

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Discussion Starter · #10 ·
tomorrow is finally gas station day. im down to two bars on the gas gauge and i have to go about 60 miles one way to the job. im thinking i could make it if the wind isn't bad and if the roads are dry but i'd prolly be running on fumes. i've never been a fan of running with an empty tank because i know fuel helps keep the impeller on the fuel pump from burning up and also keeps the pump armature cool. i have a station about 6 miles from home that i'll top off at. same place i always buy gas at, i always use the same pump, and i always stop pumping when the handle clicks. i may have mentioned prior that my previous avg on stock rims and re92's with 50 psi was 54.9. we're gunna finally find out how bad these big heavy tires are on a car with a lifetime mpg of 53.7/weak ima really is. if its not worth the penalty at $4/gal than i'll put the re92's back on. i have fallen in love with how much smoother the big tires and 40 psi feels tho.
 

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My general rule is that after the last fuel bar goes away, I have around 1 gallon of gas left.
A more advanced method is to reset TripB each time after refueling. Then you can always take the reported MPG (e.g. 70.1), multiply it by ten (e.g. 701) and then add half of the reported MPG (e.g. 70.1/2). That'll tell you how many miles you can drive to use 10.5 gallons of gas (e.g. 701 + 35 = 736 miles). So if you've driven 684 miles, then you know you have 52 miles left (736 - 684) before you're almost out of fuel.
 

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Discussion Starter · #12 ·
wow I had a busy week lately, I ended up with 53.9 mpg on my first tank with big tires on 40 psi. I think the biggest negative factor was I had about 200 miles of 70mph highway travel which is rare for me. typically, I only travel on roads that are 55-60 mph. I lost 1 mpg from my prior average of 54.9. I will admit I have had to relearn how to drive the car with the larger, heavier tire combo to maintain the good mileage. the lean burn requires some added finesse with the right foot and I have to downshift for small inclines. I'm 110 miles into my second tank and the weather has been much more favorable, dry roads with less rain and the temps have been up into the 60's. my average for tank 2 is up to 60mpg. I'm curious as to why warmer weather seems to have such a great impact on my cars lean burn. the only other factors I can think of is 1: I removed the gas cap 2: I added 80 pounds of fuel and tools. real head scratcher. my car has been bottoming out on the rear bump stops a lot more but maybe its affecting my alignment or aero, or possibly less travel in the suspension attributes to more energy being transfered in a forward positive motion?? lol, I'll have to read into this. Minnesota weather is crazy this time of year, we have had a very late spring and still had temps dipping below the freezing mark at night this week and the weather people are already talking about highs in the 80's next week. I guess i'll find out soon if increasing temperatures really have that much of an affect on my insight.
 

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Discussion Starter · #13 ·
had my 2nd tank with big tires up to 64 mpg, warm air helps my lean burn a lot, i started readin up on hot air intakes and im too lazy to build one and too cheap to buy parts, i got the ambition to open my hood and look at trying it and 5 minutes later i came up with this...
Hood Automotive tire Vehicle Motor vehicle Automotive design

all i did was disconnected stock tube and flipped it around backwards so the inlet is a few inches from the cat and i temporarily stuck a rag in the balance tube so it draws all air from the vacinity around the cat. i plugged in my scanner and did a test run, outside temp was 67 and my obd scanner said the iat was at 87. good for plus 20 and simple enough i can flip it back in a couple minutes on a hot day.
 

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Discussion Starter · #14 ·
i didnt like the rag so i relocated my balance box, i had to pull the mount off the wiper fluid reservoir and widen the two holes to get the room needed to fit the airbox, fairly simple prolly spent 15 minutes on it.
Hood Motor vehicle Automotive design Car Auto part
 
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