Hey guys,

I've recently got Potenza RE950's in the 235/45/17 size installed on my 2K1.

Installation went smoothly, they've been driven around without any problem at all.

(Yes I know there is a debate on whether or not to mount 235 on a 7" rim, but I spoke to a Automotive GURU and he looked over the tire and rim and said it was fine)


Here's my Question for you.

What is the TIRE pressure you guys are Running??

What's the fronts? and What's the rears?


Thanks,
Eric

 

^^^

 

C'mon Guys!! Help me out!

 

Empz just play around with the pressures between the factory 32 and the tires max of 40.

Try 36 front and back...don't forget to adjust when ever there is a significant temp change.

Everyday city driving I usually use 34-36, if I am going on a road trip I will go as high as 38-40. At the track (road course)where temps get much higher then the street I will drop them to 34-36 cold, a hot temp of around 40-42.

 

I'm running my 235/45 tires (Dunlops) at 40 in front and 38 in back. I may drop the pressure a little more, (I started in the mid forties). At too high a pressure, I could feel that the tire was not riding flat on the ground . . .

 

Do u have any pics of the new 235/45's? does the profile appear to be same as the 225/50's? Looking to go with same tires and appreciate your input.

 

One last question, how much wider are the 235's...an inch or so? Thanks.

 

Where did ya get'em and how much?

 

Hey,

Well the 950s are recommended for 7.5 inch whereas we have 7.0.
So its about Half an inch short on our rims. But my "Guru" said they were fine. They just might Wear a little faster, but I don't really care about that, compared to RE92s!


With the 235/45/17, you WILL get more Wheel Gap. Not exactly a good thing, but its Not really Noticeable.

I'm in Canada and I bought them off my Mechanic for $210 (Canadian) TAX In, and Installed.

So not bad.

 

i bought this tire for my audi about 3 months before i traded it in for the maxima. i fell inlove w/ the tire and told myself i would put them on the max as soon as a i could ... till i found out they only came in 215 or 235.

im real tempted to go out of spec on the tire and drive on the 235 cuz i just love this tire so much.

 

Are you betting your life on what the "GURU" said? Did he sign some kind of "guru warranty" to make you feel better?

 

he's doing what he wants, you do what you want. As long as you make sure you're never in his car, you should be all set. And don't bother with the argument about creating a hazard for other drivers because his car is 1000% less dangerous than all the 18-wheelers out there that are driving on tires so far from spec they couldn't see spec with binoculars.

You're talking about the difference between 225 and 235... come on. It's not like he's jumping to a tire 2 inches wider than spec.

 

"guru warranty"

from the FAQ - written by an engineer who has worked with nerve gas agents (so she knows stuff about 'margins of error')

In defense of running 235/45R17 tires on 5th Gen OEM rims:

There are many factors that go into setting safety standards for items like tires. The most important aspect of these in this discussion in layman's terms is the consideration of "what if...?" So what's the "what if" here? Seating of a tire in a rim has to consider adding all of the forces together that could cause a tire to be unseated, identifying the most critical, then using this as the safety design basis.

Even the most severe turn puts very little force on the tire/bead interface. First, the lever affecting the force on the rim (the distance from rim to road of 2.75") is short compared to the overall lever length (12" which is distance from road to hub), hence over 97% of the force (I won't bother with formulas) is transmitted to the center hub (the longer the lever arm, the more force is transmitted) at which point the lugs take the stress. The remaining force is distributed evenly around both circumferences of approximately 120" linear length (total of inside and outside circumference of bead length), PROVIDED THERE IS SUFFICIENT INFLATION to equalize force distribution (back to the caps in a minute). Hence even a severe turn exerts only a very small lever force that is distributed throughout the tire. Modern tire designs all use wire cable in the bead area for reinforcement to retain tire diameter at the bead, providing an additional safety margin. The CAPS above are to emphasize the lowest common denominator in the tire safety equation: pressure. Tire pressure is what seats and seals the tire to the rim and distributes peak loads throughout the tire to dispell energy. Hence the engineer's challenge and the limiting factor is maintaining adequate pressure in the tire for that dreaded unknown factor: the consumer.

As we all know, most people don't bother checking tire pressure on a regular basis. Therefore the National Highway Department and tire manufacturers have to set their standards to the lowest common denominator, a too-low tire pressure where the rim is almost to the road due to low pressure (probably around 2-3 psi). Under these circumstances, an emergency maneuver places at least a 1000-fold increase in point pressure at the tire/bead interface since it is only the bead (<2") on the outside of the rim that has to take all of the side forces of a sudden maneuver. The tire contends with an additional force here where the tire tends to "fold over" as the vehicle's weight shifts, bringing much more of a side vector force on the bead interface.

In the Ford Explorer/Firestone tire fiasco, Ford listed a recommended inflation range of 22-26 psi for a few years, actually lower than what Firestone recommended. Given the lack of maintenance that SUV owners are notorious for, in all likelihood the tires were rolling off the rim, especially in cases where the wheel dropped off the edge of the road. It is no wonder that Explorers were rolling over!

So, what do I do to ensure my own safety margin? In addition to a RSB and FSTB to distribute force equally to all 4 tires, I also visually check all 4 tires' levels before EVERY trip, maintain my tires with at least weekly tire pressure checks, and run a pressure of f/r 36/32 psi to ensure a tight and safe bead seat. [SIDEBAR: Why do I run a higher pressure in the front? To better support the front weight bias of our cars to give me more neutral handling (less understeer).]

Just to anticipate your follow-up question for the accident scenario, if I lose tire pressure suddenly (massive blow-outs don't really occur if tire pressure is maintained, sniper attacks not included!), I imagine there WOULD be an increased risk of the tire rolling off the rim. But you have to remember that in this scenario that tire is going to be a handling problem REGARDLESS without its vital air pressure.

SUMMARY: Tire safety standards are set assuming the worst case, which in this discussion is the lowest possible pressure that keeps the rim off the road for many consumers. Since I check my tires at every trip, know their height when normal, and back this up with regular (at least weekly) tire pressure checks, then I am confident that I am operating a safe vehicle at 104% width compared to guidelines.

CAVEAT: I am NOT recommending this choice for all of you, this is MY choice as you might consider me an outer fringe high-risk taker. I am currently starting a business to commercialize a new chemical process to make hydrogen peroxide by directly reacting hydrogen and oxygen gases, certainly a hazardous operation if not done carefully (remember the Hindenburg!). I also have worked with rocket fuels and components for binary nerve gas agents, so I am VERY aware of safety considerations in designs of equipment and materials. Tires that are properly inflated are critical to my own safety and that of my family, and safety is an essential consideration at ALL times.

Credit: RsMaxMaggie

Source: http://forums.maxima.org/showthread.php?threadid=131766

 

This topic has been beaten to a bloody stump. All the relevant information is in the FAQs. If you want the facts, that's where you'll find them.

 

My concern with tire and rim width is not safety, specially running 235 ona 7" rim.

I am always concerned with performance of the ratio. It's always better to have the widest rim possible for a given tires size. E.G a 195 on 6" wheel is better then a 205 on a 6" wheel. I remember a test a long time ago whent the smaller tire gave better traction and lap times then the bigger tire.

The problem with big tires on smaller wheels is you start to round the tire and the edges don't make contact to the ground. Fine for everyday driving but not for getting the last ounce of traction which can make the difference in winning.

 

Just curious...where exactly is the 'last ounce of traction' needed? Street racing? Road courses? If this is autocross, why not just get a dedicated autocross wheel/tire combo and not belabor the point for street tires?

 

Read the thread again...I said "it's fine for everyday driving" which meas the street and when I said "winning" yes I meant the track. My researched and experienced opinion applys to dedicated wheels/tires as well.

Should I rewrite my thread so children can understand? Or should you learn to comprehend what you read before jumping all over it think you have a smart *** answer?

 

Listen bubba, just because you can't admit to being wrong, no need to assume everyone else is child or can't understand.

Smart-*** answer? I asked a legitimate question for which you got all defensive. Just do us all a favor, grow up.

 

Explain to me where I am wrong?

 

Hey 2k2wannabe, I totally agree, I often see bimmer with tire that bulge and this come strait from the dealer, most american car that you see on the street have tire that bulge, check the Grand Prix GTP their tire bulge by 1/2 inche on almost every single one I see.

Cheers

AA

 

 

i'm waiting for the reply

 

I just wanted a simple answer not another Flame Fest in here!


AS for my "Guru", which will remain nameless at this time. He said this setup would not endanger the occupants of the vehicle, and if he told me that I will believe him.

I'm sure his 30+ years of Rally/Track Racing, Automotive Tuning, and all his winnings that he's had in is Younger years should be sufficient for me, who is only out to get a Decent Alternative for our strange Stock size.


-=-=-=-=-=-=-=-=-=-=-=-
By the way ... when Jackie Chan races his Mitsubishis in Macau, my "guru" use to be his Technical Advisor!

If its good enough for Him .... its BY Far Good enough for me.

 

Read my Post above ... and U'll understand why I don't worry!

 

I don't have any pics of the new tires, but dimensionally they look VERY similar to the OEM size. The sidewall does bulge a little more than the OEM tire, but not much at all. If you do the math, you will discover that the overall height of the wheel should be almost identical to the OEM tire when a 235/45 is used. I have not noticed any increase in the "wheel gap" everyone seems so concerned about. What I have noticed is that the tread is noticably wider than the OEM tire. It makes the wheels look much better IMHO when viewed from the rear of the car. So far, I've ridden on the Dunlops in both rain and freezing rain and they absolutely blow away the RE92's in terms of wet grip. Before replacing the tires, I was scared to even drive the speed limit or hit small puddles of water on the highway. I have tested the tires and I have newly found confidence in driving the car in the wet. I would have to say that overall I'm very pleased with the tires. I ordered them from Tire Rack and they were not too expensive. I think about $120 each.