galwahh

Hello All! I've got the stock aluminum slotted gold 14 inch rims on my 86 Berlinetta - original sizes were either a 195/70 or a 205/70 - will a 225/60 fit on that rim ok and will it fit on the car? and what about putting a 225/70 on the back, would there be any problem with that?

Chris Knight

iTrader: (2)

I'm actually in a similar boat. Lining up to buy a Berlinetta that has the same rims. The RPO is QHX which is "Tires, P205/70R14 Blackwall (Standard on Berlinetta)." Most of the tire websites are pointing me towards 205/75R14 as standard equipment though bc there's not a specific selection for Berlinetta.

So the 205 is width of the tire tread in millimeters (MM). The number after the / is the sidewall height, which is a percentage of the width. So for the standard tire my car came with, it's 70% of 205mm is the height = 143.5mm SW height. This is already taller than the 245/50R16 an Iroc had (50% of 245mm = 122.5mm SW height).

205/70R14 - 70% of 205mm = 143.5mm (QHX Stock Berlinetta)
205/75R14 - 75% of 205mm = 153.75mm (Online proposed for Stock Berlinetta)
225/60R14 - 60% of 225mm = 135mm (I would say this size would fit without issue)
225/70R14 - 70% of 225mm = 157.5mm (1.4 inches taller than Stock Berlinetta but only a hair over the proposed for online)
245/50R16 - 50% of 245mm = 122.5mm -> ~148mm to account 16" rim (Stock Iroc)

This thread may help as a reference: https://www.thirdgen.org/forums/whee...ptions-my.html

My question to add to the discussion is the speedometer readout. Since the "Star Ship" Berlinetta has a digital speedometer, does anything need to be changed if the tire size is changed to get a correct readout? I'm between getting new tires for the 14 inch rims or finding a set of 15/16 inch rims.

galwahh

Hi Chris, thanks for chiming in. i think i'm going to go with the BFGoodrich radial T/A - pretty much a standard and one of the few brands still offering a selection of 14" - but i'm still undecided between 215/60 and 225/60...i supposed the 10mm width and 6mm side wall height differences are not even noticeable, but if anyone has any pics with the berlinetta rims, post them up!

Great question about the speedo my guess is that changing the size will cause an incorrect reading

Chris Knight

iTrader: (2)

It just depends on the size you would be going with. If you went with the initial combo of 225/60 F and 225/70 R, you'd probably notice as the diameters would be 2" different from each other and a slight "hot rod" tilt.

Went ahead and was messing around with tire sizes just to see what would be closest across the board for stock rim sizes. Each sidewall height is the closest choice to be truest to the original size. This doesn't account if the tire width will mount on the rim width either. The MPH are in there to give an idea of how the size change would affect speed. So the the underline is going to be the closest in each rim size to the original but those tire sizes don't exist . So in bold are my choices of a potential tire that do exist.

205/70R14 - 79.5" circumference - 100.0% - 35.0 @ 35mph - 70.0 @ 70mph - 100.0 @ 100mph = ±0.00%
205/75R14 - 82.0" circumference - 103.2% - 36.1 @ 35mph - 72.2 @ 70mph - 103.2 @ 100mph = +3.19%
215/60R14 - 75.9" circumference - 095.5% - 33.4 @ 35mph - 66.8 @ 70mph - 095.5 @ 100mph = -4.51%
215/65R14 - 78.6" circumference - 098.8% - 34.6 @ 35mph - 69.2 @ 70mph - 098.8 @ 100mph = -1.17%
215/70R14 - 81.2" circumference - 102.2% - 35.8 @ 35mph - 71.5 @ 70mph - 102.2 @ 100mph = +2.18%
225/60R14 - 77.4" circumference - 097.4% - 34.1 @ 35mph - 68.1 @ 70mph - 097.4 @ 100mph = -2.65%
225/65R14 - 80.2" circumference - 100.9% - 35.3 @ 35mph - 70.6 @ 70mph - 100.9 @ 100mph = +0.86%
225/70R14 - 83.0" circumference - 104.4% - 36.5 @ 35mph - 73.1 @ 70mph - 104.4 @ 100mph = +4.36%

215/60R15 - 79.1" circumference - 099.4% - 34.8 @ 35mph - 69.6 @ 70mph - 099.4 @ 100mph = -0.56%
225/60R15 - 80.6" circumference - 101.3% - 35.5 @ 35mph - 70.9 @ 70mph - 101.3 @ 100mph = +1.31%
235/55R15 - 79.1" circumference - 099.5% - 34.8 @ 35mph - 69.7 @ 70mph - 099.5 @ 100mph = -0.48%
245/55R15 - 80.5" circumference - 101.2% - 35.4 @ 35mph - 70.9 @ 70mph - 101.2 @ 100mph = +1.23%

225/55R16 - 80.9" circumference - 101.8% - 35.6 @ 35mph - 71.2 @ 70mph - 101.8 @ 100mph = +1.76%
235/50R16 - 79.4" circumference - 099.8% - 34.9 @ 35mph - 69.9 @ 70mph - 099.8 @ 100mph = -0.19%
245/50R16 - 79.1" circumference - 101.4% - 35.5 @ 35mph - 71.0 @ 70mph - 101.4 @ 100mph = +1.37%
255/45R16 - 80.5" circumference - 099.0% - 34.6 @ 35mph - 69.3 @ 70mph - 099.0 @ 100mph = -1.04%

235/45R17 - 79.6" circumference - 100.1% - 35.0 @ 35mph - 70.1 @ 70mph - 100.1 @ 100mph = +0.11%
245/45R17 - 80.7" circumference - 101.5% - 35.5 @ 35mph - 71.1 @ 70mph - 101.5 @ 100mph = +1.51%

If you're sticking with the factory rim, stick with the factory size 205/70R14. Why? - It's a 14inch rim! You're not going to be autocrossing the thing or tearing up the drag strip on it. If you must have a bigger contact patch, go with 215/70R14 as the speedometer difference won't mess with you much. Best penny-pincher choice as you own the rims. If you don't plan on EVER souping up the car, must stay/like the original styling, or just don't have the money for expensive wheel upgrades--go this route.

Inherit or find a super cheap set of 15 inch rims, go with 215/60R15 as none of the other sizes exist. It's a tiny bit smaller in circumference. You'll be slower, odometer will roll over faster, and you gain barely any contact patch. Personally I would just...no...just no.

For a 16 inch rim I have to go with the sleek Iroc rims. Go for the stock size of 245/50R16 and you've got tire choices which have been tried and proven. Go a tad faster, odometer will roll over slower, and you gain contact patch. Still have to buy the rims but you can find some sweet deals out there for a set ($400, $300, less?). If you like the stock Iroc look (2 choices), find said rims for cheap $300 or less, or must have OEM or bust for performance upgrades--go this route.

I said this was for stock sizes but I have to level with you. They aren't making 16" and smaller rims for a reason, so you're limited on your choices for tires. With a 17 inch rim, you get a LOT of after market choices and tire selection grows. Go with a 235/45R16 here as the circumference only grows 1 inch bigger. Bigger contact patch and same ride height. This *can* the most expensive option but *can* also be cheaper than going stock on a 16 inch (all in the choices). Example: A set of Machined black Irocs on eBay goes for ~$600, well some of that can be made up in the tire price (if not all of it). If you want wider selection, have a bit of extra money available, and don't mind a slightly harsher ride--go this route.

Keep in mine any rim/tire combo beyond stock will require to look into fitment, back spacing, etc. https://www.thirdgen.org/forums/whee...ire-sizes.html Ride quality will vary also. The larger the contact patch, the more it's going to follow the grooves in the road. The shorter the sidewall height, the more you'll feel the road via bumps and such. There's a lot of information out there on the subject and this is just how I am looking at it.

Given this is going on a Berlinetta which is focused on "luxury," I'm leaning towards sidewall height as the primary factor, followed by contact patch. With an LG4, I'm going may lose every red light race but I'm determined to do so comfortably. First choice for me will be keep the stock rims and get a Uniroyal Tiger Paw tire set (which ever size I mentioned is currently cheaper). Second choice is acquire a cheap 88-90 Iroc 16" set and refinish so the stripes and openings are gold to mimic the stock rim; paired with a BFGoodrich G-Force set.

Chris Knight

iTrader: (2)

A quick follow up to my post. This website here gives some pretty good information on the stock Camaro rims from 1982 to 2002. Lists the rim dimensions, back spacing, bolt pattern size, material, and finish.

http://www.tacreationsusa.com/camaro_wheels.htm#Chrome

If going with a non-stock rim, this website breaks down how to figure out your back spacing. It's been linked to in multiple posts already.

http://www.skulte.com/adapterfaq.html