Do I have enough room ... Tire Size Question

Tire Size Question ... What should I do


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MrBlvd

Registered User
I would like to increase the tire size on my car. I currently have 235 45 17 mounted on a 17 x 7.5 wheel with 40mm offset. I would like to go to 235 50 17. I've reviewed lots of prior posts and from what I've seen, the 50 is the preferred size for this size wheel. However, due to the fact that the wheels I have are not made for our cars, I believe my clearances are tighter than if I had the stock backspace..............The wheels were on the car when I purchased it and this is my first time purchasing tires for the car. Due to the amount of fender gap, I was hoping to put 255 50 17 but after some research quickly determined that this would require some major spacers/adapters which I really don't want to deal with at this point. I tried to test fit a 245 45 17 but the tire guy was afraid he was going to damage my wheel....This confirms a comment posted by XR7 Dave on 9/11/02 "Mfg's recommended wheel widths mean about crap.".... I can get a good deal on some AVON 235 50 17s from tirerack.com but I don't want to order them if they won't fit. If this is the case, I guess I will have to get the 235 45 and then lower it to get rid of the gap. I really want the larger tire to mellow out the ride. What do you think? Will the 50s fit?
 

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I would go with the 235/50ZR17's If I were you. I sell wheels and tires all day long and that is close but understand this. The strut is not moving in or out, so you have some room to play. Like with my car, I lowered it 1 1/4 inch and I want the Cobra R's but am afraid the 2355017's will rub the fuel neck in the right rear. Play it safe. Those wheels are what, a med pos offset? That is tight but with the 50's you should be ok.
 
Wheel Spec's

Wheels are Vault 311 Vortex 17 x 7.5 , 40 mm offset which I believe is classified as high positive offset, lug pattern did not match up and the prior owner used some creative enginnering to open up the thru holes for the studs. Inserts used behind lug nuts. I'm almost apologetic when the "tire guys" see them for the first time. I like the looks and I haven't had any issues other than fitment. 23lbs ea. bore dia.73.1 so hubcentric rings are used.
 
I have the 17x7 Silver Cobras and have 245 45s..... they're tooooo low profile on an unlowered car, but the width is nice. I'd like to have a wider tire on the back. I'll stick w/ a 245 width though.
 
Picture info

Sketch made in CADKEY using the dimensions from the pictures and tire dimensional data. I will e-mail a copy later today...will send a couple of different formats to you. Keep in mind it is a sketch...I know for a fact the tire profile is wrong ... however, the clearances were drawn based on my measurements...Note the radial dimension for the tire section width is wider than the profile I drew...again this is based on what I see on my car...installation of the tire on the min. sized wheel must cause the section width to "shrink" as opposed to installation on the largest wheel size?????
 
MrBlvd said:
I would like to increase the tire size on my car. I currently have 235 45 17 mounted on a 17 x 7.5 wheel with 40mm offset. I would like to go to 235 50 17. I've reviewed lots of prior posts and from what I've seen, the 50 is the preferred size for this size wheel. However, due to the fact that the wheels I have are not made for our cars, I believe my clearances are tighter than if I had the stock backspace..............The wheels were on the car when I purchased it and this is my first time purchasing tires for the car. Due to the amount of fender gap, I was hoping to put 255 50 17 but after some research quickly determined that this would require some major spacers/adapters which I really don't want to deal with at this point. I tried to test fit a 245 45 17 but the tire guy was afraid he was going to damage my wheel....This confirms a comment posted by XR7 Dave on 9/11/02 "Mfg's recommended wheel widths mean about crap.".... I can get a good deal on some AVON 235 50 17s from tirerack.com but I don't want to order them if they won't fit. If this is the case, I guess I will have to get the 235 45 and then lower it to get rid of the gap. I really want the larger tire to mellow out the ride. What do you think? Will the 50s fit?

A 235/50/17 is a stock sized tire for the SC (overall dimension). It will fit much better and ride better as well. It will have a narrower tread contact patch than the 235/45's. Your current tires are too small anyhow.
 
Placed order today --- went with 235-50-17s

(4) 235 45 WR17s delivered $550.00<br>
AVON Ultra High Performance All Season<br>
Made by Cooper specifications developed by Tire Rack<br>
I will let you know how they fit and drive
 
Here is a picture of the clearance I have on the front tires when running a 255-50 17 with a .250 spacer between the rim and the hub. Not much but enough.
 

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Here is another on the rear. The emergency cable is not on the car in this picture but comes close to the rim and could rub so I zip tied it away from the rim.
 

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Super XR7 ... A few questions for you

What type and size wheels do you have? Do you know the offset and backspace?<br>
Where did you get your spacers? Did you have to modify for the bolt pattern or have you swapped your hubs?<br>
The AVON tires from tirerack have a 30 day return w/o any sort of prorate ... so I can still change my mind! :D I would still have to pay shipping costs two more times though :(
 
You said you didn't want to mess with spacers. Also not sure but I think Mike may have wider than 7.5" wheels and he did not say what his offset is. I feel that in most cases a 255/50 is too wide for good fitment on your wheel.
 
MrBlvd said:
What type and size wheels do you have? Do you know the offset and backspace?<br>
Where did you get your spacers? Did you have to modify for the bolt pattern or have you swapped your hubs?<br>
The AVON tires from tirerack have a 30 day return w/o any sort of prorate ... so I can still change my mind! :D I would still have to pay shipping costs two more times though :(


The tires are Bridgestone Potenza 255-50 17's.
The front hubs were changed to 96-97 (larger ring mounting dia.), I made the concentric rings for the rear hubs as I just changed out the bearings and not the hub housings.
I made the spacers out of alum and are .250 thick.
The rims were made for the Thunderbird (Detroit Wheel bought off Ebay from a place in Florida) are 17" x 9" and the mounting bolt circle is 4.25". I can not remember the back spacing but I believe it was 36mm.
 
They Fit Just Fine

Just had the tires mounted and everything is A-OK! Thanks for everyone's input. I will take a picture tomorrow and post so you can see the clearance. Much more than I thought. :D
 
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