255/45/17 tires on 17x7.0" wheels? What promblem to exspect?

[QuickSilver]

I need tires with a higher load index on my '92 Q45. I want to mount 255/45/17 tires on my 7.0" wide wheels.

What promblems will this cause? How uneven can I expect the tread wear to be? Are there are safety issue or performance loss with this set up?

[pmkls2]

I am unsure about your load range problem, but if you check I think that you will find that for a 255 45 17 they probably recommend at least an 8 inch wide rim. I a mrunning 17x7 rims on my 240 with 225 45 17 tires and if I remember correctly the next size up from that calls for an 8 inch wide rim so you would be even a couple more sizes too big. Do some checking on that though. The Tire Rack website offers charts on tire sizes and rim recommendations.

[QuickSilver]

You're right, a 8.0" rim is recommended for a 255/45/17 tire. If I plan not follow their strict recommentions, what problems will I have with safety or contact patch problems will I have?

[Grant@tirerack]

You need to have at least an 8" wide rim with that tire size. Even if they were able to squeeze them on that narrow of a rim, they won't handle well at all. They will tend to tram line and follow any grooves in the road since the tread will be crowned. Not a good idea.

[szh]

You may also have serious problems with the bead not sitting properly (i.e., flat on the edge of the metal) on the rim! This could be dangerous on curves and high lateral acceleration situations.

I would go with a narrower tire and be more careful in this regard!

Z

[QuickSilver]

Thanks Grant, I was hoping you'd chime in. Just the type of explaination I was looking for.

Now, if I were willing to sacrafice some handling performance for some "looks" without spending more for new wheels--- What's the optimal handling size tire for a 17x7 wheel and what the worse?

How important to handling is it to match the OEM diameter of 26.0"?

How better or worse the handling be with 245/45/17 tires? Shouldn't the 10mm make a big difference?

[Exar-Kun]

20 dollars says you find more information posted by me tan you could ever need if you hit search and put in "contact patch"

mysel;f and others have delved into great length about that issue.

try running a 235-50-17, I belive thats acceptable for a 7" wheel, and supports the correct load index(im shooting from the hip)-

-chet

[szh]

Here is a link to an older post of mine (on page 2, about seven posts down) that lists a bunch of 17" tires that will work well on various 17" rims. You have to make sure that the rim range is the correct size, etc. It shows you estimated speedo error, prices from three sources, etc.

http://www.nissaninfiniticlub....ber=2

If you want the original Excel spreadsheet directly, rather than from this earlier post (I have added some prelimirnary info on M45 tires too), drop me an e-mail.

Z

[QuickSilver]

Thanks again guys. My choices are definately limited with the 7" wide wheel. I bought them not too long ago for my old Maxima, but now they're inappropriate for the Q. Hopefully, I'll be in the market for some take offs in a few months.

235/50/17 would be a great size but seem to be only one or two brands in that size and will be expensive.

Z, that is some extensive research you did. If understand your notes correctly, the only size that works with 7" wide wheels is the 255/50/17. Does the extra 25.50mm {(127.50 -114.75)x2} in height lessen potential promblems in mounting and handling?

Did read your research correctly? Is a 255/50/17 tire a better compromise than 255/45/17 or 245/45/17 in regards to handling and mounting safety?

If the answer is yes, I may take a chance in trying the BF Goodrich G-Force T/A KDWS in a 255/50/17 size.

[QuickSilver]

The best compromise may be the 225/55/17 Falken Ziex 512 with a load index of 97W. The diameter is 26.7", but I can adjust to that.

Falken Ziex 512's are also available in 235/45/17 with 97W load index, but I my limited experience I think these will ride too "rough." I currently have 235/45/17 Nitto NT555 with a load index of 93W and it seems like I could easily damage my cheap wheels.

Z, I'm still interested in hearing your opinion/reasoning on 255/50/17 on a 7" wheel. I'll check the websites of some the manufacturers in the mean time.

[QuickSilver]

BF Goodrich G-Force T/A KDWS, Bridgestone Potenz RE 750 and Kumho Ecsta 712/ASX are available in 255/50/17 tires with 101W load indexes that are approved for a 7.0" wide wheels.

Unless you guys have a strong preference, I'm going to go with the BF Goodrich's at $130 each because of the 400 wear rating. The Bridgestone's and Kumho's have a wear ratings of 340 and 280, respectively. The Kumho Ecsta ASX are rated at 420, but don't seem to available yet at the discount tire shop.

[szh]

Hi, Quicksilver.

Sorry I have not responded sooner - been on a business trip (and am typing this at the airport! ) I will look at the spreadsheet and let you know some thoughts. My concern about the wider tire would be that its height is larger and there would be some speedo error. More importantly, if your wheel offset is not right, then you will have a problem with tire touching the suspension or the fender rim on curves and bumps! This would not be good for the tire.

I will post more sooner as soon as I look at my spreadsheet again ... I gotta run catch my flight!

Z

[Grant@tirerack]

The BF Goodrich would be the best wearing but the Potenza RE 750 is going to be the best for handling both in both wet and dry conditions.

[QuickSilver]

Hi Z,

Thanks for the note. No need to check the spreedsheet again. The sections that applied to me are totally accurate. The spreedsheet is incredibly useful to us Q/M45 owners. Sticky post maybe?

Grant,

Thanks for your advice and opinions. The BF Goodrich will save me quite a few bucks that with go towards suspension and/or wheel upgrades. When those are up to par, I might me able to appreciate a more expensive and better performing tire.

Do you still think I'll have noticeablely poorer handling performance, despite the manufacturers' approval of a 7.0" wheels with this size?

[QuickSilver]

Oh, I think I'm o.k. in regards to the offset(40mm). I'm looking foward to having a the wheel well filled in abit more. The 235/45/17 set-up now looks and feels far from stock. As of now, I don't plan to lower the car.

[szh]

Hi, Quicksilver.

My flight from Newark to Chicago has been delayed. I am sitting on the plane, but we are going to be here for another hour. Argh! I hope I do not miss my connection in Chicago). Fortunately, American Airlines is cool about using my laptop and 1XRTT wireless data connection, so I can post this.

With regard to the 255/50-17 tires, my thoughts would be as follows:

1. The diameters are typically 27.1", so the speedo error is about 4.5%. This means that indicated 60mph would be about 62.8 - 62.9 mph. Just be aware of this (avoid those speeding tickets when going faster. ) This error is small enough that it should not affect the transmission shift points, etc., but you may want to get Q45Tech to respond to that thought too!

2. The offset of the wheels you are planning to use should be in the 38mm to 40mm range, else you might have rubbing against the suspension (if you use 45mm for example) or the rim (if you use 30mm for example). I am not absolutely sure of this, however, and Grant would be a better person to ask about this. Tire Rack may have done specific tests for this fitment!

3. The tires are certainly strong enough (in the 101 load index range).

4. I would avoid the 245/45-17 sizes since the rim width needs to be 7.5" at least. This is a popular size for available brands and tires, though!

5. The 235/50-17 is another good size, but the good tire there (the Michelin Pilot Sport AS) is expensive. Ouch.

6. I believe that the Continental ContiExtremeContact is another option in the 255/50-17 size, but I am not sure what rim width it needs - the Tire Rack web site did not show that data - so you may want to ask Grant that question.

Hope this helps!

Z

[QuickSilver]

Z,

Wireless data connection and a new M45, cool. Do you also have V1 radar dector? I've got to move it up on my list after the safety issues are taken care of.

Yes, helpful as usual. I will double check on the offset. I'll post something about the transmission shift points on Infiniti General forum. I've got a '93 TCU in my '92 Q, so the shift points are are different from stock. It may be a deal braker. Good point.

I think ellewso is using some inexpensive Continental tire and is dissatisfied with them. I'll check with him directly.

[szh]

Do you also have V1 radar dector?

Yes, I have had a V1 for years and it has saved me from a bunch of tickets. I recently "upgraded" to the latest version to get improved laser detection performance. Only Valentine Research has an upgrade program - for a smaller cost, you can essentially get a brand-new detector and turn the old one in.

Z