sb66

I have been looking at new wheels for my '85 - I am pretty enamored with the american racing torque thrust 2 - style wheels (I have seen many amazing looking vettes here with those (and other style rims))

I have been using wheel size.com to try to help get something close to fitting like stock - 16 x 8.5 +32mm 255/50vr - 16's

For those running torque thrust 2's - what size are you running on your c4's?

I was thinking 17's to keep it close to original size?

any thoughts and opinions would be appreciated

thanks very much

Sean

hcbph

Sean

Remember anyone with a 88 and up will have +56mm backspacing instead of the +32 or +38 (depending on width) that your and my car have.

I don't have the ones you're looking for but I did do a upgrade on mine a couple of months ago. I went with 18's just because I expect the 17" tires will soon be similar to the 16's in availability. Right now there's a whole lot more 18's available than 17's, and a whole lot more 17's than 16's.

sb66

thanks hcbph

I did notice that tire choices were scarce for the 16" 1 or 2

the 17" torque thrusts were able to get +32 or + 33mm offset - using that site you sent me got almost all of the clearances very close to original - - how are those 18's for you?

Sean

hcbph

Sean

It's sweet!. Same width as the originals, within 2mm of the originals and not even close to rubbing. Exact same diameter (tires) as the originals. If you didn't know better, you would not notice there was any difference between what was and what is, even the speedometer is right on. I have to say though, I think the new rims are sexier looking than the originals but that's a personal opinion. Given the choices, if I had to do it again I'd do it in a heartbeat.


Paul

sb66

so I guess the other question I have is - using the rim and tire size calculator - which of the categories at the bottom is most important? circumference, scrub radius, or the other clearances - it seems most of the wheels I have looked at can meet the clearances, but the circumference and this scrub radius(?) are harder to get close to the originals -

thoughts? - this is new to me so all this info is is like scrambling eggs in my head - not that there was much up there to begin with

Sean

c4cruiser

If you can get the Torque Thrust II wheels in a 17x9.5" dimension with a 38mm offset, you can use a 275/40-17 tire and they will mount fine with no clearance issues. The OEM 255/50-16 and 275/40-17 tires have very close to the same measurements such as tread width, section width and diameter.

Get 4 wheels and tires that are the same sizes; that will allow you to rotate the tires for longer tread life. IMHO, the 275/40-17 tires will be around for some time. Lots of brands have that size available and there are also competition-only tires still available in that size.

sb66

I found a set of torque thrusts that are 17 x 9.5 with +32 and +33mm offset. I was using the site that hcbph gave to me before about rim and tire size calculator. I was using the 275/40 17 tire size as well. but when hcbph mentioned about the circumference, I started to wonder if that was more critical??

you mention the 38mm offset - is the 32/33 ok?

thanks

Sean

sb66

https://www.summitracing.com/parts/a...9561/overview/

if this works

c4cruiser

A 32 or 33mm offset should not be a big deal as the difference is just a few mm. But it might be a good idea to contact American Racing to check if that specific wheel center will clear the brake calipers on early C4 Corvettes. Also ask about the 83.06mm bore diameter; you want to make sure the wheel is hub-centric and that the hole is the correct size for the C4 hub. Other people here are using the TT II wheel and I haven't heard any issues about fitment.

As far as measuring tire circumference, most tire makers list the diameter of a given tire size as mounted on a wheel. But things like wheel width and tire pressure can slightly change either measurement. That can affect speedo readout to a small degree.

You should be OK with the wheel (but confirm with AR )and I still recommend going with a 17" wheel and 275/40-17 tire. For tires, look at the NITTO 555G2.

hcbph

Sean

Make sure of the numbers. 5 mm difference equates to about 1/5"
The original rims on yours and mine are either `6x8.5 +32mm back space or 16x9.5 +38mm backspacing.
Just insure you're getting what you think you are. If you want something to align as the oems did, use these numbers and go from there.

sb66

very good - I did get a little wrapped up in the 32mm number - forgot to double check the other

thanks

sb66

https://www.wheel-size.com/calc/?whe...cl=30mm&sr=0mm

(hopefully the link works)

if I am looking at these correctly - how do they look spacing and alignment wise?

I really have little knowledge of much of this - I do want to get it right

hcbph

Sean

I'm no expert on rims and backspacing which is why I did like you and asked a lot of people and posted a lot of questions before putting my $$ down.

As I understand backspacing is how far from the centerline of the rim to the mounting surface of the rim. Based on that understanding, if you have 2 rims with the same backspace but different width, based on that understanding if the rim is 1" wider the extra width will be split between the inner and outer width of the rim. Meaning your rim will be 1/2" closer on the inside and extend out an additional 1/2" than the oem rims.

Being the oem 16x9.5's were +38mm backspacing, if you want something to fit close to oem location, try to get closer to +38 if you can.

On the tires noted, they have a smaller diameter than the originals so basically your speedometer will run fast.

The tires and rims will extend 10-13mm further both on the inside and outside vs the oem ones. Get out your tape measure and start measuring to see if that's acceptable on your car or not. You don't want rubbing or scraping particularly at full lock turns.

Good luck.

WVZR-1

OP - I don't use or rely on the "web calculators" but generally speaking they can be used for general research. Don't rely on using the calculators for anything other than casual research.

C4cruiser mentioned things that you need to be concerned with.

When comparing wheels I use the largest known OE that was used during production. For the early C4 that was a 9.5@38 so I do all calculations using that specification.

Doing the math, the specifications for BS and OFFSET mentioned in your link are a "match". You want that confirmed by AR - voice or electronic matters likely not but knowing who or having documents is important.

The center-bore can be compensated with hub-rings. For wheels with larger than OE center-bore I've used hub-rings always.

Ask AR if they have a "caliper template" for these wheels. They will understand your question I'd think. I'd think no issues but ASK!

You want to confirm with the vendor the same information and confirm the return-ability if they aren't as mentioned in all correspondence.

The numbers "hint" a match/will work and no problems but NOT until confirmed. Using the numbers it could almost be considered a "better/more desirable" fit.

sb66

thanks all - I did not realize all that goes in to this wheel change

sb66

The tech at Jegs said that the torque thrust wheels are "lug centric"(?) and would work perfectly for the application

I am still waiting to hear back from American Racing with regards to the other sizing

sb66

sb66

sb66

sb66

need a better background - messy garage

17 x 9.5 - +32mm with Yokohoma 275/40 r17

steering and ride - to me - seem greatly improved -