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Tire size

3881 Views 26 Replies 8 Participants Last post by  26634
I'm an admitted dork when it comes to tire sizing. I ordered new wheels for my 69 based on what everybody says fits - 17 x 8 with 4.75 BS for the front and 17 x 9.5 with 5.5 BS for the rear. Where I'm confused is tire size. The fronts seem to be pretty standard - 235/45-17. It's the rears where I'm confused. Some run a 275/40-17 and others run a 255/45-17. What's the difference in the sizes and which is most likely to clear without rubbing?

Also - my current tires are 235/60-14. Which of the above mentioned rears come closest in height? I'm concerned about my speedometer being off. It's pretty accurate with the 235/60-14's. Thanks!!
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The 275s fit but they are very tight. If you want NO rubbing go with the 255s. DJD uses 255s because he wanted no rubbing and he does at times load the back of his car down. You may also get some rubbing with the 275s when you go over curb cuts. The most important thing to keep in mind is these cars are not all the same. 40 years in some cases has taken it's toll. I think the 255 stretches out nice on a 9.5 wheel maybe someone can post some close ups of a 255 and a 275 mounted on a 9.5 wheel.
Hi Al i have the 275/40-17 rear and the 235/45-17 front . I run the nitto 555 all the way around and really like them , the rears don't last very well i can't figure that out .
I think Mark would need a 475..... to hook up. :)

The 255 is a safe bet on a '69 and that's what I run. BFG's
Al, the sizes you mentioned would be very close in HT, with the 275 being just over an inch wider.

255 is a lot of tire for a 9.5" rim, I'd try the 275. They seem to fit pretty well on almost all 69's from what I read here.

Going over the edge, huh? 'bout time, you'll like it.
A 275 tire on a 9.5 rim is only 1/4" wider than a 255 tire on a 8 inch rim. Just a thought.
Thanks, guys. For those of you running the 275 on a 9.5 rim on a 69 - any rubbing? I've already used a body saw and hacked away the outer wheel houses so they are exactly flush with the quarter panel lip. At the top of the wheel well, I have exactly 12" from the inner wheel house to the quarter lip and I'd rather not do any more cutting in there.

Jim - over the edge indeed! It would be tough fitting the new brakes inside my 14" rallys. I've already found a buyer for my wheels and tires, as well as for my factory front discs, and it will offset the cost considerably. I really like the look of the rally wheels on these old cars, and I'm sure I will miss them. The billet rallys are godawful expensive and out of the question for me.

But onward and upward, as they say:)
12" should be enough. I'm in the process of rolling my lips and I'm getting 12" also when I'm done. The 275 tire measures 11" total.

Total rim width of a 9.5" rim is really 10.5" with a 275 tire the bulge comes out to be 1/4" SO a 10.5" rim with 1/4" bulge on each side = 11" total

If you measure the correct backspace from the inner well, at least 1/2" that will leave you 1/2" to the outer lip. Should be fine.
I run a 275 on the rear and had a little rub at first, but a shimmed that tire out 1/4" and where it was hitting on the inner fender I just bent that in about 1/2", can't tell, no rub, also, it has been lowered one inch.
A 275 tire on a 9.5 rim is only 1/4" wider than a 255 tire on a 8 inch rim. Just a thought.

Thanks - but how much wider is a 275 tire on a 9.5 compared to a 255 on a 9.5?
Thanks - but how much wider is a 275 tire on a 9.5 compared to a 255 on a 9.5?
Around 1 inch. I wouldn't put a 255 tire on a 9.5 inch rim though. A 255 tire measures 10.1" a 275 tire is 11" and the rim measures 10.5 inches. It would look funny with the tire being sucked in on the rim. Thats why the 8" rim makes only 1/4 difference, because of the bulge.
Mine don't look funny, at least not to me.
Mine don't look funny, at least not to me.
Isn't your rim wider than your tire?
I looked when I got home and you're right if you're talking about the tread width. However, in my opinion it doesn't look funny, it just has the low profile look to me. I looked at my other vehicles and some appear to have tread width smaller than the rim and others appear larger (lots of wheels in my driveway). I will agree that a 275 might look best and I'm all in for the wider is better in this case. I'll also say that it looks like the 275 should fit just eyeballing it allowing about 1/2" on either side as compared to the 255. Besides that others are running them now. I might even give them a try next time around. It's just my opinion that there's nothing wrong with the 255 either. :)

Edit: I'd go with 275's on my '67 without concern when I get the chance.
OK...Thats why we have out own opinions..:thumbsup: Like I always say It's your car , you make it how you like. I have a thread going now with 4 types of wheels and it happens that the lowest rated wheel is the one I like the best.:p I may get the one I like. IT's MY CAR.:beers:
I like all the choices in your poll. I wish my budget would allow to have various sets of wheel tire combos to change out from weekend to weekend. I'll bet I'm not the only one with that idea. It is amazing how much wheels and tires change a car. :thumbsup:
Just as a point of information (and no other reason) according to the Tire Rack (using Sumitomo HTR Z II as an example) the rim width range of a 255/45-17 is 8 - 9.5 the section width is 10.3 on an 8.5 wheel (on a 9.5 wheel it's 10.7 (.2 for every 1/2" of wheel width) and the tread width is 9.1. The 275/40-17 is 9 -11 the section width is 11.1 on the 9.5 wheel and the tread width is 9.9. The point being the tires would appear very similar in size because of the wheel width. The choise is yours you can play it safe and go with the very slightly smaller appearing tire or take a chance and maybe have to make accomodations for the 275. The best bet would be to try and borrow a 275 on a 9.5 from someone and try it. That may not be possible but maybe someone has the wheel fitment tool or a 275-15 that you can use to judge from. Good Luck with whatever you choose.
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