Rear wheel lip 1/4" smaller than front lip - will it be noticeable?

[RF GTO]

I've been obsessing over this and I'm thinking it might not be as big of a deal as I'm thinking. I recently purchased some 18" Torq Thrust Classics (the one's with the grey) for a 67 Pontiac Lemans. The fronts are 18x8 w/ 5" of backspacing and the rears (because I have the 68-72 wide style rearend) had to be made at 18x9.5 w/ 6.75" of backspacing.



This puts the rear lip 1/4" smaller than the front. I'm sure if you really analyze it the difference might be noticeable, but will it be that noticeable?

[Rhino]

Considering that it's a cast wheel, I would imagine the 1/4 of difference is actually in the wheel mounting pad, rather than the front lip.
I have a set of 18 x 9.5 cast wheels. The fronts are 45mm offset, the rears are 20. That equates to just over an inch of difference in backspacing, however the wheels are absolutely identical on the front side.

[Northeast Rod Run]

Did you actually measure the lips on each rim, or are you just assuming because of the spec sizes?

If you measured and they actually were smaller, I couldn't live with that

[RF GTO]

I haven't actually measured them. I'm just assuming based on the measurements. I placed the order for them just a few days ago so I'm thinking I might be able to change the specs if I move quick.

I'm hoping what Rhino had to say is the case with regard to Torq Thrusts.

[Northeast Rod Run]

Since you haven't measured them, I would feel it's a safe bet that the rear lip is going to be AT LEAST 1" bigger than the back, and probably closer to the 1 1/2" mark

[RF GTO]

Thanks, that makes me feel much better about it!

[JRouche]

I've been obsessing over this and I'm thinking it might not be as big of a deal as I'm thinking. I recently purchased some 18" Torq Thrust Classics (the one's with the grey) for a 67 Pontiac Lemans. The fronts are 18x8 w/ 5" of backspacing and the rears (because I have the 68-72 wide style rearend) had to be made at 18x9.5 w/ 6.75" of backspacing.

This puts the rear lip 1/4" smaller than the front. I'm sure if you really analyze it the difference might be noticeable, but will it be that noticeable?

Well, just doing the math and knowing they are the same type of wheel it might look a lil odd if the back lip is smaller (like the car is backwards?) And you have your math correct. You are spot on!!!

You dont need to measure them in hand to know what the wheel lip is gonna be if you have the numbers. They give the wheel measurements for a reason, so you will know before buying them, right? Isnt that how it works, I dont get the whole idea of waiting till you get them to measure them. What? Just to make sure they maybe got it wrong and hopefully it will work out in the mail? NO!!! Doesnt work like that. Numbers are numbers, they dont lie. Manufactures give numbers for a reason, takes the guess work out.

You bought four wheels. The fronts are 8" wide (actually prolly 9" wide) So you remove the 5" from the 8" and that gives you 3" on top (facing out) of the wheel mounting surface ( Im not including the extra 1/2 on each side for the tire bead lip, thats where an 8" rim is actually a 9" rim, 1/2" of outer (each side) wheel that they dont count in for wheel measurements).

So the fronts have 3" out from the wheel mount (not including the 1/2" rolled edge).

The rear wheels are 9.5" minus the (large) 6.75". That gives what???!!!! Yup, 2.75". And really, its only a 1/4". Not much to scream over.

It might look just fine, specially if you have a fatter tire, meaning somewhat of a larger tire thats meant for the rim. Say you make the rear look even larger.

But no matter how you measure it, the rear wheels will have a smaller lip, 1/4" smaller. Thats not dramatic. Not something I would sweat.

And GTO, you have it correct. You already got the numbers down. I just didnt get the talk about waiting till you get the wheels to measure them. It is what it is. JR

[Rhino]

You dont need to measure them in hand to know what the wheel lip is gonna be if you have the numbers.

With a cast wheel you do absolutely need the physical wheels for a 100% definitive answer. The outward appearance has everything to do with the actual casting used, rather than the backspace/offset. To decrease costs the manufacturers pour the wheels with the exact same mold for a wide range of offsets. They're made with a large wheel mount pad, and then machined it down to spec. Unfortunately, since these are two disparate castings, we have no method for comparison.
Granted, I've never owned a set of TQ's, but the vast majority of cast wheels work this way.

I would also agree that to 99% of the people looking at the car wouldn't even notice if the rear lip does end up being smaller.

[RF GTO]

Thanks for your help guys! I read everyone's posts, analyzed and re-analyzed everything, and ultimately decided to change the specs. I'm going to have to run a spacer on the front anyway so I had them increase the backspacing a 1/4" to 5.25 on the front and decrease the backspacing on the rear a 1/4" to 6.5 so that I will be guaranteed to have at least an extra 1/4" on the rear.

[camino70]

Can't you ask the supplier/manufacturer what the lip measurement is before ordering?

[DriverzInc]

It's simple math, and a 1/4" deeper front wheel ain't cool, glad you made a change. The centers are all casted, and in the A/R CL205, they don't mill down the pad to obtain offset, they are sent out with the same pad length. So your wheels would have for sure, had a bigger wheel lip front than rear.

If I spec'ed the wheels out I wouldn't have let my customer make that mistake without at least trying to change his mind by pointing out the obvious, the other option could have been a 7" front wheel, but glad to hear you made the change.

Who lets their customer do that?