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Discussion Starter #1
Ok, I have done the search and am not finding this specific question. I am in need of new tires for my SVT T-Bird wheels, but want to go as wide as possible. I was wondering opinions and/or experiences with a 255/45/17 on a 7.5" rim. Most of the tire retailers say 8" is as skinny of a wheel as they recommend for the 255/45, but I figure an extra 0.5" is not that significant. If someone has pictures of this size on a 7.5" that would be appreciated.

Thanks,
Kevin M
 

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Ok, I have done the search and am not finding this specific question. I am in need of new tires for my SVT T-Bird wheels, but want to go as wide as possible. I was wondering opinions and/or experiences with a 255/45/17 on a 7.5" rim. Most of the tire retailers say 8" is as skinny of a wheel as they recommend for the 255/45, but I figure an extra 0.5" is not that significant. If someone has pictures of this size on a 7.5" that would be appreciated.

Thanks,
Kevin M
It's a slow day at the office so I did some googling.

"If the rim is too narrow, the flex point moves toward the shoulder area, creating heat buildup in the shoulder, which reduces tire life and could result in failure."

"A narrower rim pulls the beads closer together, curving the sidewalls. This increased curvature allows the sidewall to flex more readily over bumps and absorb more road shock during driving. This offers a softer ride"
http://www.dunloptires.com/care/widthRatio.html

"Good for offroading"
"Wouldn't worry about going .5 inch too narrrow"
http://www.expeditionportal.com/forum/threads/1617-Tires-on-too-narrow-a-rim

"2 years w/ .5 less and no issue"
"Smaller contact patch in the corners"
http://forums.bimmerforums.com/forum/showthread.php?t=89159



-g
 

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It's a slow day at the office so I did some googling.

"If the rim is too narrow, the flex point moves toward the shoulder area, creating heat buildup in the shoulder, which reduces tire life and could result in failure."

"A narrower rim pulls the beads closer together, curving the sidewalls. This increased curvature allows the sidewall to flex more readily over bumps and absorb more road shock during driving. This offers a softer ride"
http://www.dunloptires.com/care/widthRatio.html

"Good for offroading"
"Wouldn't worry about going .5 inch too narrrow"
http://www.expeditionportal.com/forum/threads/1617-Tires-on-too-narrow-a-rim

"2 years w/ .5 less and no issue"
"Smaller contact patch in the corners"
http://forums.bimmerforums.com/forum/showthread.php?t=89159



-g
That's good stuff Kevin M but I hope you read it correctly. For instance, a 45 tire is a lot different than a 70. There is a whole lot less sidewall to adapt.

I also wonder about the narrower rim sealing better. Look at the profile of a tire bead. Which part of the bead does the seal, anyway? I always assumed in was the inner lip against the rim flat part... so if that bead is torqued in it will tend to curl up away from the flat.
A long time ago IIRC a regular on Mustang group said he was running narrow rims wide tire and found hard cornering to loosen the inside bead on the outside tire in a sharp left turn.

Sidewall flex -thus heat- moving up toward the tread also presents a problem, if not to the tread overlay area, to the belt; which is relatively stiff compared to the sidewall.
I dont think that inner tire failure prior to tread wearout is limited to economy tires, either. Others could address this better than I can but it's part of the build cost/ warranty paradigm. They are not just looking at road hazard events but at heat/flex caused failure.
IOW you will have a hard time collecting in a lot of cases.

just sayin...
 

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If someone has pictures of this size on a 7.5" that would be appreciated.

Thanks,
Kevin M

No .. the wheel Width range with a 255/45/17 Tire is between 8" to 9.5"

Just use a 245/45/17 ..

I have 255/50/17's on my SC, except my wheels are 9" wide.
 

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To my knowledge my current rims are mb motoring rev's which are 17x7 with a 40mm offset. I currently run 255/50/17's all around with shaved front upper control arm ball joint studs. I have no issues with rubbing and it's probably the biggest tire width wise I could fit on those rims.

Yep the only width rev's were ever made in were 7". So I am definitely running a bigger tire then they suggest on a smaller rim then they suggest, but damn does it look and grip good.


 

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Ok, I have done the search and am not finding this specific question. I am in need of new tires for my SVT T-Bird wheels, but want to go as wide as possible. I was wondering opinions and/or experiences with a 255/45/17 on a 7.5" rim. Most of the tire retailers say 8" is as skinny of a wheel as they recommend for the 255/45, but I figure an extra 0.5" is not that significant. If someone has pictures of this size on a 7.5" that would be appreciated.

Thanks,
Kevin M
Kevin, I believe that the SVT T-Bird wheels are 7", not 7.5". 235/55R17 is a nice fit on those wheels, and that size is about 27" tall, which looks good in the MN-12 fender openings.

Here are some pics of that size on those wheels, and installed on an SCCoO member's car:

http://www.sccoa.com/forums/showthread.php?t=120690


cheers
Ed N.
 

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Discussion Starter #7
Thanks for all the replies. I think I have made my decision. I have decided to just go with a 255/50/17. This tire is listed as being approved for as small as a 7" rim and should fill the wheel wells good. I actually have a 235/55/17 on the car now so this will be a little bit shorter than those, but give me the added contact patch that I want. I am now second guessing if the wheel is really 7 or 7.5 so this should be a safe tire size. I remember from when I have balanced them myself that they measured 7.5, but they may be spec'ed as 7". Oh well the 255/50 should work well. Thanks again.

Kevin M
 

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Too bad you are not closer to Tn. I have 4 17x9 Cobra R's, and want to swap 2 of them for narrower 17x7 1/2 to fit narrower tires on the front to use with my manual rack & pinion.
 

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Discussion Starter #9
Even if I was closer I am not sure I would trade for those as that is part of the problem. I have so much money tied up in these wheel because I had them chromed as Ford never offered them in chrome, so I really don't want to part with the wheels for another set. My other option was to have the rears widened so that I could run drag radials out back, but I am too cheap for that too ($165/ wheel).

I actually got the tires installed yesterday. As I went to remove the wheels from the car I noticed my current size was 235/50/17, so I redid my math and realized the 255/50 was too tall, so I ended up with the 255/45 and they look great. The installer even said that they went on pretty easily.

Thanks again for all the input.

Kevin M

Too bad you are not closer to Tn. I have 4 17x9 Cobra R's, and want to swap 2 of them for narrower 17x7 1/2 to fit narrower tires on the front to use with my manual rack & pinion.
 

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255/50/17 is closer to the original tire size and won't throw off the speedo as much, but it is tall and wide and requires clearance of the excess from the upper control arm ball joint. Some people are afraid of doing this. However either way I'm sure you'll be happy with the wider tires. So what brand and model did you choose?
 

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I actually got the tires installed yesterday. As I went to remove the wheels from the car I noticed my current size was 235/50/17, so I redid my math and realized the 255/50 was too tall, so I ended up with the 255/45 and they look great. The installer even said that they went on pretty easily.

Thanks again for all the input.

Kevin M
Glad to hear it worked out. 235/50/17 is quite a bit shorter than the original tires, 255/50 are a bit taller. The 255/45 you went with should be on 8" wheels, so just keep an eye on the wear in the centre of the tires in case they are being bulged out. 255/45 is about 1/2" shorter than stock, one of the best compromise choices in 17". 245/50 would have been ideal if you were set on something a bit wider than what you had, but there aren't many tires offered in that size.


cheers
Ed N.
 

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Discussion Starter #12
I went with the Nitto 555's. The car is actually down right now for a PI motor upgrade and all I am waiting on is the exhaust manifolds to arrive and then I will have her back together and get to test out the new rubber, but I am pleased with the looks/fit thus far. I know I need to get it aligned ASAP as the old tires were very worn on the insides. Does anyone know what the alignment specs need to be on our cars with the 0.75" drop Vogtland GP springs? I am afraid that most shops are just going to pull the stock numbers and that is whey my tires were wearing the way they were.

Kevin M
 

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Good choice. I like the Nitto's. Talk to Rob about the right numbers. He just did an alignment on mine and it was all screwed up before he set it right.
 
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