I just got off the phone with the chief U.S. engineer for the Pirelli P7000 SuperSport series tires. He's going to check with Pirelli corporate, but he's relatively certain that the P7000 SuperSport in size P245/45R17 has a minimum acceptable rim width of 7.5", not 7.0" as indicated on the Pirelli web site. He based his assertion on published specifications from the Japanese, European and American Tire and Rim Associations. Without exception, all three of these associations specify 7.5" as the minimum acceptable rim width for 235/45R17 and 245/45R17 tire sizes from ANY manufacturer.

I asked Pirelli's engineer about the dangers of running tires on rims with too narrow a width. He stated that doing so increases lower sidewall stress levels beyond the tires' design limits. In extreme cases, this could lead to sidewall separation.

 

The minimum rim width for the Goodyear Eagle F1 GS EMT in size 245/45R17 as published on Goodyear's web site is 7.5". Check out:

http://www.goodyear.com/us/tires/tir...GSEMTSize.html

So that means that all 3 tire manufacturers that published a 7.0" minimum rim width for their 235/45R17 or 245/45R17 tires have either corrected their rim width size to 7.5" or are in the process of doing so.

In the final analysis, it appears that 225/50R17 is the widest 17" tire size than can be run on a 7.0" wide rim, maintain the proper geometry, and remain in spec.

 

I've been doing some homework too. It appears that 225-55-17 is within specs. The minimum for this size is 6" and maximum is 7" (7.5 on one tire). The diameter goes up a little, but this seems like a good resize. There are over 28 tires available in this size. What do you think?

See my spreadsheet. The top portion is for 16" stockers. The rest is for 17"

http://paulwendy.com/maxima/tires.xls

 

225/45R17 is also a popular size. The problem in using either of these tire sizes is that you throw off your speedometer readings.

The best tool I've found so far to compare tire size differences and their effects on speedometer readings is located at:

http://www.miata.net/garage/tirecalc.html

Compared to the stock tire size of 225/50, the speedometer discrepancy is 3.42% too slow for the taller tire (225/55R17) and the same amount too fast for the shorter (225/45R17). That amounts to about 2.5 mph at 70 mph. So with 225/55R17s, you'd actually be traveling at 72.5 mph when your speedometer says 70 mph and with the 225/45R17s, you'd be traveling at 67.5 mph. As long as you keep that discrepancy in mind and make the appropriate adjustments in driving speed, you should be all right going with either tire size.

BTW, I've heard that the ABS system might be affected by running tires that do not maintain the proper geometry. I haven't seen anything in print to support this contention, however.

Last but not least, the maximum rim width you refer to is actually the measured rim width. Most 225 tires will fit just fine on 8.0" wide rims.

 

heheh INTERESTING.......i been saying this all along. And like i said, juss cause the manufacter claimed whatever doenst make it fact.....235 or 245 is juss too wide for a 7"

 

dont forget, with the 225/45/17s you'll be gettin lower mileages so when it comes time to change wheels ect you'll be a few percent off, same with whatever else in the engine. and with the 225/55/17s, vice versa.

 

My biggest complaint about the maxima is that it bites in the rain. I cringe everytime I see a puddle.....and then hold on for dear life!!! Wider tires will make this even worse!! I am all for having a little better traction on take off...but there are some horrible effects that happen to a wide tire in water. Most cars are engineered to ride on a certain tire....widening it might give you traction but it might give you the opposite effect. I had a pickup that I put 235 BFG's on and the traction got worse because there is less weight per cm/in of rubber. Wider tires track horribly....more expensive, and are downright scary in the rain.

Speaking of tires....what tire would you guys recommend for decent snow and water conditions for the stock 17" rim?

 

Sad but true.

 

I was going to get the Bridgesone Blizzaks (ones with directional tread, heard they were very good in rain, snow, and ice) but moved to Virginia and don't need snow tires. I couldn't find any 17" snow tires in TireRack.com I was going to get new 16 inch rims for them also, but didn't need them either anymore.

 

Now, lessee here. My max reads 1mph high/30mph indicated, so @70mph, my speedo really reads just above 72mph.

So if I get 225/45R17's, it'll correct my speedometer error?

Someone else reported their speedo reads high too. Maybe the max was actually designed for 45 profile tires in the first place.

This is starting to sound encouraging.

 

Get them mounted on 15 inch steel wheels, that is what I did.

You will want at maximum a 205/65R15 and if I had to do it again I would have gotten a 195/70R15 for better traction on ice and in deep snow.

 

I did timed 20 km runs on cruise and my speedo was off less than 1km/h.