16 or 17 inch rims for 1984 Caprice?

I had previously made this chart for tire size comparison purposes. Maybe it will be some help:

Tires: Keep within +/- 4% for odometer error, target RPM 684-742
(More RPM's = smaller diameter tire.
(revolutions per mile)
Size: ....................Diameter:.........Width:.......................R.P.M.
225/75/R15.............28.29.............8.86...(stock size)....713.3
225/70/R15.............27.40.............8.86.........................736.4

235/70/R15.............27.95..............9.25........................721.9
235/65/R15.............27.00..............9.25........................746.6
235/60/R15.............26.10..............9.25........................773.0

245/70/R15.............28.50..............9.65........................707.9
245/65/R15.............27.54..............9.65........................732.7
245/60/R15.............26.57..............9.65........................759.3

255/70/R15.............29.10............10.04........................694.5
255/65/R15.............28.05............10.04........................719.3
255/60/R15.............27.05............10.04........................746.0

265/65/R15.............28.56............10.43........................706.5
265/60/R15.............27.52............10.43........................738.2

275/65/R15.............29.07............10.83........................694.0
275/60/R15.............27.99............10.83........................720.9




245/65/R16.............28.54..............9.65........................707.0
245/60/R16.............27.57..............9.65........................731.8

255/65/R16.............29.05............10.04........................694.6
255/60/R16.............28.05............10.04........................719.4

265/60/R16.............28.52............10.43........................707.5


225/65/R17.............28.52..............8.86........................707.6

235/65/R17.............29.03..............9.25........................695.1
235/60/R17.............28.10..............9.25........................718.0

245/65R17...............29.54..............9.65........................683.1
245/60R17...............28.57..............9.65........................706.2

255/65/R17.............30.05............10.04........................671.5
255/60/R17.............29.05............10.04........................694.7

 

Lets stay real here, a factory stock full size 84 Chevy and aerodynamics just don't work in the same sentence, what hub caps you decide to use won't change anything gas millage wise, looks yes, gas millage no, not gona change a thing


But Muffler Bearings, that will give you gas millage........40MPG, up hill both ways.

 

Based on Krash's info, I wouldn't go with the 215/70/15. They're at least an inch smaller in diameter than the stock size. It's just going to increase how much open space is in your wheel well openings, and make the tire look to small for such a large car. There are plenty of 225/75/15 options on Tirerack, starting at $375 for a set of five. Oh, and the least expensive Hankook option has white walls.

 

Thanks again. I have P205/75R15s on it now though, So it's actually a fifth of an inch difference (The P215/70R15s being the smaller) between tire sizes. Sure though, P225/70R15 is three tenths of an inch larger than what's on the car.

And a bit off-topic but I think something like this pictured below will make for better fuel economy on the highway, Aerodynamic-wise (With care that it's attached securely!)



That's a belly-pan. They can be made with panels that come off for oil changes. (Also note I've read people who tried these sometimes had overheating problems, Though not always - It depends on the pan. Still, Care is to be done if making one of these. Some race-cars have these pans.)

EDIT - I found a LRR P225/70R15 - 27.4 Inches in Diameter and it says "44 PSI Max" and it's a highway all-season tire.

http://www.tirerack.com/tires/tires...GRHTSOWL&vehicleSearch=false&fromCompare1=yes

 

Even before I read your post, just looking at the pics before reading......... Over Heating (and carbon monoxide poisoning came to mind), not MPG and aerodynamics. 'IF" your building your Chevy for the Bonneville Salt Flats, belly pans and aero-sky-phonic hub caps would be the ticket. But as I understand it, your just after a nice daily drive and you have a nice car IMO, reminds me of my 77 Impala 4 door sedan from years gone by. Just my 2-bits of nothing, but seriously think about what you may want to do to your Chevy and get REAL advice if your after MPG, not just blown out of the exhaust pipe claims.

 

Well thanks, I understand that if it's done in a certain way overheating can happen so safety first! Someone posted at Ecomodder.com that his car nearly caught on fire because he had a belly-pan on over the gas-tank. I do believe there are some gains to be had when safely done though.

By the way, Do Pontiac Parisienne (brother/sister model car) Skirts fit the Caprice Sedan?

 

Not positive, but I would think they would.

EDIT: Hold on - now I'm not so sure. compare your 1/4 panel wheel opening to the wheel opening on the Bonneville Brougham. Yours has wheel opening flared a bit, where the Bonneville's opening is flat.

 

The Bonneville uses a different quarter than the Caprice, so the fender skirts won't work. My 84 Delta 88 had 205/75R15 tires from the factory, and that was with the handling package. 225/70R15 is the smallest I would go for on these cars. They do work well. The 205s were hopeless.

Never mind Tedy's muffler bearings. Think on this one: 84 Delta 88 2 door, 307/200R-4 and a 78 Buick Electra Limited, 350X (Buick)/THM 400. Of the two, the Buick was not only the faster, but it got slightly better gas mileage, compared to the Oldsmobile. When looking for mileage, it is the torque curve of the engine combined with gearing that gives that to you. The more torque, the further down in the revs, the better the mileage. It really is that simple. Tires make a big difference too. On your Caprice, the factory specified 35 psi, which happened to be the maximum pressure for the tires that were available on the car. I have that same with my 88 Grand Marquis. I run my 225/70R15s at the max pressure on the sidewall of the new tires, 44 psi. Works a treat, and I've never yet had any tire have funny wear patterns. Keep in mind I'm a fairly high mileage driver, too, and I regularly get at least the factory specified mileage out of a set of tires, and often more. The difference between running a 45 psi tire at 35 or at max can be as much as 100 miles per tank.

 

Is that with or without your aerodynamic hubcaps?

 

Tedy, you are running light trucks on the Estate Wagon. Do an experiment, THEN comment about tire pressure. Set your tires to the 35 psi on your door sticker, and drive for 300 kms. Then pump the tires up to their max, and do the same route. Fill up after each run and you will see a very significant difference between the two runs. Try it before you make one more snide remark.

 

Sometimes what seems very obvious can be very wrong when it comes to aerodynamics. My dad used to run at the wind tunnel at Ford in Dearborn back in the 70s. I remember him telling me about the Triumph TR-7s and their "wedge" design The perception was, they would cut through the air, but the fact was they would have been more aerodynamic if they had turned them around and run them backwards.

Things like choice of hubcaps can affect how effectively the brakes cool. There were issues with full-face non-vented hub caps preventing the air from circulating around drums/rotor.

Likewise, skid plates, belly pans, grill design, air dams, and other aero-effects can prevent air circulation around the radiator and engine. They could also cause issues with turbulence that actually cause more drag.

For what its worth...

 

I do run my truck tires, Goodyear Wranglers at 35 all the time and also do not experience any od tire ware nor do they have a "low on air" look to them compared to the 50 psi max rating. I'm not going to argue that at max psi the tire would roll better either, but for the maybe 5 miles extra you would get out of a tank of gas IMO it's not worth having my teeth rattled out keeping the tires at max psi.

Do I have the know all the answers if it comes to fuel economy, heck no! Best I can say is, keep your car tuned, don't floor the gas peddle at every green light, and yes make sure your tires are properly inflated.

Call me what ever you want, hate me for life I don't care! I'm not going to sit idly by and watch a young guy who is trying to learn get misinformation, you have a proven record of train wreak when it comes to fuel economy BS and it's treads like this where your locomotive starts chugging, you start off with a couple good points and before we know it will turn into 40 MPG again. Not just myself but other members who actually know what they are talking about, who build engines that have questioned your credibility or lack of in many other threads. Maybe the best thing I could teach 101 would be to post up some of those fail threads?

 

Firm believer the BEST MPG is controlled by your right foot more than anything. Sure you can pick up a tenth here and there with this mod and that but you will see more improvement by setting your cruise on 65 mph. You will usually see a couple mpg gain but I have so much fun driving my cars and my dad's car I don't worry much about mpg. I figured up my '92 RM and get between 21 and 25 mpg hwy depending on what time I get up for work. I figured the '55 once and it gets 14 to 15 with a 423 HP SBC and I figured the Malibu once at around 10 mpg but putting a 502 BB, 3 speed trans and 3.73 gears mpg never once was a thought. Enjoy your car for what it is!

 

i was looking at summit for rims for my 1987 pontiac safari, they had a good selection

 

Thanks again. I'm thinking of going with the 225/70R15s I posted on Page 2.

As for MPG mods, I'm thinking of sticking some engine pre-heaters in it. They do help even in the summer, Imagine reducing the engine warm-up time by half an hour and warm starts to also extend engine life.