Max tire size, I'm breaking my brain

[Hubbarocks]

So... I know I'm beating a dead horse here. Reading through many posts about tire sizes on cars. I understand everyone should take their own measurements, so i did. I'm going cross eyed trying to sort out what Back spacing & max tire I can squeeze in that would be optimal on the REAR only at this time.

Holding no one accountable, from experience what should I expect to look for regarding a rim size OR do I pick out the actual tire first and find a rim from that I think I'm doing it wrong.

My Measurements on my poor drawing below for my 1969 charger. Any insight would be appreciated!!

 

[70ChargeDodger]

It's a pretty good drawing actually.
My 2 Chargers have 275/60/15 w/ lots of room to spare on 8" rims, w/ approx. 4-4 1/2 backspace.
That is the sort of standard as I am sure you know.
I am always looking for 10" rims w/ the correct backspace (4 1/2- 5 1/2?).
Tires also seem to go up in price dramatically after 295/50/15 fyi.
Good luck.

 

[66Satellite47]

I suggest taking another measurement. Take the outside measurement higher up in the wheel well. On my '66 Satellite the tire contact point was well up in the wheel well, not the lip. Not sure what the '69 Charger out wheel well looks like. You need to pick both the tire size and rim backspace at the same time. Get the overall tire section width, not just the tread width & diameter ratio.

 

[Beekeeper]

Although not a Charger on my 69’ bee a 15” x 10” with 5.5” backspace and a 295/50 tire clears.

 

[Hubbarocks]

I suggest taking another measurement.

yup i have this. my current wheel is 4" from that bump. never rubs. She sits pretty high with the HD leaf springs. although i'm not opposed to removing or modifying the bump if it causes issue with the new set up.

i'll need to go either 16 or 17" wheel in the back. i think that may be a mistake now , the tire choices seem limited

 

[33 IMP]

First, I would pick a wheel diameter. It really doesn't matter, because you can get a 15"wheel with a tire diameter of 26", and a 20" wheel with the same tire height. I say to start with the wheel diameter so you can shop for available backspace.
Next, decide on a wheel width, keeping in mind that a given tire will have more section width on a wider rim. An 8/8.5 width is fairly easy, assuming the backspace isn't crazy one way or the other. A 10" width is a lot harder to fit.
Now, looking at your diagram (which is not bad at all, btw) I would have said you need 1/2 more backspace than half rim width, then I noticed the rear isn't centered. But that is a roundabout way of saying..... you are centered in the passenger wheel well, so you need a centered wheel.
Some younger guys like the metric offset bullshit (I'm old, I dont) but yours is easy...zero offset. Shop for zero in whatever width, you should be good.
If you use backspace, remember that bs is measured from the back edge of the wheel, but the width is measured between beads, so an aluminum 15x10 is really eleven inches thick. So a centered 15x10 would have 5.5 backspace.
What tire to choose, is ENTIRELY dependant on which wheel you choose.
(Long way of saying, I agree with beekeeper, that's about the max you are gonna get under there, and having the open wheelwell of a charger, and the *** in the air sure helps. A low-sitting rr is much tougher)
Edit. Avoid 16" wheels like the plague, tires are drying up more than the 15s. 15s for a classic look, 17s for a modern,wider, tire selection. I have 16s on a camaro, and had 16s on a mustang. Selection and availability is terrible.

 

[66Satellite47]

yup i have this. my current wheel is 4" from that bump. never rubs. She sits pretty high with the HD leaf springs. although i'm not opposed to removing or modifying the bump if it causes issue with the new set up.

i'll need to go either 16 or 17" wheel in the back. i think that may be a mistake now , the tire choices seem limited

If you have the ride height you want go with it. I agree with 33, the 16" tire selection is poor. Match the wheel width to tire size you choose. I have no experience with 17".

 

[furious70]

17's e getting trickier as well to find, make sure you can get something you like before buying the wheels

 

[Hubbarocks]

so no on the 16s then. (appreciate that)
the search continues. hunting for 17x9 with 4.5 ~ 5.0 BS.

the front i have wilwood 12" disc im converting to, that has a 3.1" center bore, which is the hard part. They claim they might clear some 15 in. wheels, but i've been sending the print to some wheel mfg with no success , which is why I'm just looking for larger 17. but lots of 17's have smaller then the 3.1 center bore.

( currently have 14x7 cragar s/s all the way around) i've had these forever & trying to find something similar as far as the wheel goes

i have a 26" tall tire currently i'd like to get taller if i seem limited to go with Nitto 275/50-17 or stay with 26" tall, which seems to have more choices.

choices are hard sometimes , like trying to pick which flavor ice cream i want (lol)
argg.

 

[Hubbarocks]

here is the wilwood brake drawing

 

[Hubbarocks]

so do you believe the "section width" is accurate on these postings? can i trust it ? i know it would vary as 33 mentioned... but how much

looking at this tire on this wheel. says less then 11 inch section width (10.9) and the wheel should be centered in the wheel(ish) with 4.5 in BS on a 17x9

https://www.summitracing.com/parts/are-vn3097865
https://www.summitracing.com/parts/mtt-3470


so if i utilize those measurements and go by mine , using the minimum measurement from each side (6.5" from drum to inner fender / 6.75" from drum to leaf spring) i should have 1.0" fender side clearance & 1.5" inside clearance to leaf spring.

am i doing it right ??

 

[33 IMP]

That wheel is a little narrow for that tire, which will also mean the section width is going to be less.
Personally? I would do it. The combo should fall under your charger, and I LOVE your wheel choice. Just know those are a street/strip tire, and won't go 40k miles.
(I have a 15x10 version of that wheel, one piece, and it WONT go under your charger. 3 1/2 bs. Also have a 15x12 version, custom shop, on my opel. I love those wheels)

 

[Hubbarocks]

thanks 33, it would be a little change for me

the other option i found would be the Nitto https://www.summitracing.com/parts/nit-211320

Thanks again as always for your advise

 

[Nipper]

Pay close attention to the section width. That extra bulge in the sidewall is what will get you in trouble.Easy to overlook.

 

[66Satellite47]

I have found the specs on the Summit site to be right on. Going narrower on the recommended rim size does reduce the section width some. But the wear pattern on the tread gets narrower.

 

[33 IMP]

thanks 33, it would be a little change for me

the other option i found would be the Nitto https://www.summitracing.com/parts/nit-211320

Thanks again as always for your advise

I actually have 555 g2's, 245/50x17 on the back of my 57 sedan delivery, on 17x8s. A little taller, a little narrower. A nice tire, it will last a lot longer than the mickeys..... but won't have half the traction.

 

[Hubbarocks]

darn it... i see what your saying , that wheel was 17x8 (not 17x9 as i thought). I'm looking at too many wheels.

ideally a 17x9 with 4.5 BS would be perfect... but trouble finding this in that style with the center bore needed



i found similar wheel at 17x9.5 with 5.56 BS that should fit that tire better. it still has a 3.27 center bore and offered 17x7 (4.0 BS) for the front so will fit my brakes. using my bad math skills. i come up with 1.19" clearance to the leaf spring & 2.56" to the wheel well. American Racing said it would fit according to their scale (for what ever that's worth) they mentioned to add another 1/2" each side for the lip cutting down to (0.69") + what ever the tire budge would be (about 0.34") ... am i cutting it too close on the inside or am i going to have .35" gap?

https://www.summitracing.com/parts/are-vn21579565

i also see the Nitto "taller" tire , https://www.summitracing.com/parts/nit-214020

which may bee good for me since i have the extra height clearance.
i like the idea of a taller tire if i can. Just to decrease cruising speed's RPM & fill out the wheel well more.
275/50-17 at 27.87" tall (vs. 26" tall) or am i better off with the 275/40 i wonder ??

 

[Hubbarocks]

I actually have 555 g2's, 245/50x17 on the back of my 57 sedan delivery, on 17x8s. A little taller, a little narrower. A nice tire, it will last a lot longer than the mickeys..... but won't have half the traction.

33 - do you have a pic, id like to see it ? maybe i'll just roll with the 17x8 and that tire just to be safe!

& stop racking my puny brain on this ... tires are like ... super important guys (LOL)

 

[Cranky]

If you are stuck on wheels that you like and will fit....except for the center bore, that can be machined. For instance, I have a set of 17" H2 Hummer wheels on my 97 Dodge 2500 diesel that the center bore was 1/4" too small to fit. Wasn't hard to throw them up on a milling machine (or a large lathe) and machine that out. Not sure what a machine shop charges these days for doing that but I'd do it for a C note. Thing is, have to make sure there's enough meat to machine out.....

 

[33 IMP]

darn it... i see what your saying , that wheel was 17x8 (not 17x9 as i thought). I'm looking at too many wheels.

ideally a 17x9 with 4.5 BS would be perfect... but trouble finding this in that style with the center bore needed



i found similar wheel at 17x9.5 with 5.56 BS that should fit that tire better. it still has a 3.27 center bore and offered 17x7 (4.0 BS) for the front so will fit my brakes. using my bad math skills. i come up with 1.19" clearance to the leaf spring & 2.56" to the wheel well. American Racing said it would fit according to their scale (for what ever that's worth) they mentioned to add another 1/2" each side for the lip cutting down to (0.69") + what ever the tire budge would be (about 0.34") ... am i cutting it too close on the inside or am i going to have .35" gap?

https://www.summitracing.com/parts/are-vn21579565

i also see the Nitto "taller" tire , https://www.summitracing.com/parts/nit-214020

which may bee good for me since i have the extra height clearance.
i like the idea of a taller tire if i can. Just to decrease cruising speed's RPM & fill out the wheel well more.
275/50-17 at 27.87" tall (vs. 26" tall) or am i better off with the 275/40 i wonder ??

33 - do you have a pic, id like to see it ? maybe i'll just roll with the 17x8 and that tire just to be safe!

& stop racking my puny brain on this ... tires are like ... super important guys (LOL)

Sorry, no pic. I KNOW I had one, but I suspect it is on an old tablet that died, and I'm a long ways away from the car at the moment.
That 17x9.5 should also work, though it should be a bit tighter than the eight inch (obviously). Remembering that it is really 10.5"wide, it has an extra 1/4" offset to the inside. That should be insignificant on the pass side, and desirable on the drivers side. And I always prefer the taller tire, they just look better on our cars. But again taller or shorter tires work just like a rear gear swap. Example, if you're running 2.76, you would want a short tire, for some extra go, if you're running 3.91, the taller tire can tame the gear down. 3.23s, you can choose either. Either 275 should have the same section width. I personally would choose the taller tire.
The 17x8, with a 245/50x17 would probably fall on your car, its snug on mine, but my 57 wheelwell is quite a bit smaller than yours.