# Tire sizes **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [April 11, 2009, 6:57pm UTC](https://community.cartalk.com/t/tire-sizes/28990 "2009-04-11T18:57:54Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![daedalus](https://avatars.discourse-cdn.com/v4/letter/d/ee59a6/32.png) [@daedalus](https://community.cartalk.com/u/daedalus)\ **Post date:** [April 11, 2009, 6:57pm UTC](https://community.cartalk.com/t/tire-sizes/28990/1 "2009-04-11T18:57:54Z")
Recently my wife picke up a nail in the sidewall on the tire of our Nissan Pathfinder 4x4.we drive it about 7500 mile a year and seldom in snow or on dirt road. Several shops refuse to sell me just two tires. Our current budget makes money something of a issue so I am think about better used tires with orginal sizes called for in owners manual 235/70/15 as opposed to the 235/75/15 that are on there now. What is the best safest way to go? ---
**Author:** ![mcparadise](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mcparadise/32/32_2.png) [@mcparadise](https://community.cartalk.com/u/mcparadise)\ **Post date:** [April 11, 2009, 7:07pm UTC](https://community.cartalk.com/t/tire-sizes/28990/2 "2009-04-11T19:07:44Z")
Go elsewhere. A place that refuses to sell you what you want won’t be in business long. All four tires should be the same size, but they don’t all have to be new at the same time. Your vehicle is 4WD, not AWD. Matching circumference is not a critical issue with 4WD. Put the newest tires on the REAR. ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [April 11, 2009, 9:36pm UTC](https://community.cartalk.com/t/tire-sizes/28990/3 "2009-04-11T21:36:45Z")
I wouldn’t have mis matched tires on the vehicle. If you’re going to buy just two tires then buy the same size that’s currently on there. ---
**Author:** ![daedalus](https://avatars.discourse-cdn.com/v4/letter/d/ee59a6/32.png) [@daedalus](https://community.cartalk.com/u/daedalus)\ **Post date:** [April 14, 2009, 4:34am UTC](https://community.cartalk.com/t/tire-sizes/28990/4 "2009-04-14T04:34:18Z")
Thanks. As the tire wear is different on the front and the back I like to replace two and put them where they do the most good. I have heard about putting the best tires on the back of a front wheel drive before. So I’ll go that way ---
**Author:** ![andrew\_j](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@andrew\_j](https://community.cartalk.com/u/andrew_j)\ **Post date:** [April 14, 2009, 11:19am UTC](https://community.cartalk.com/t/tire-sizes/28990/5 "2009-04-14T11:19:52Z")
Dependent on year Pathfinders finally upgraded to selectable AWD, 4wd or 2wd. ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [April 14, 2009, 1:36pm UTC](https://community.cartalk.com/t/tire-sizes/28990/6 "2009-04-14T13:36:00Z")
Since when where they available in AWD…I’ve owned 2…90 and 98…and when I bought my 4-runner I also looked at the new 05 pathy’s. They all came in either 2wd or 4wd…AWD was NEVER an option. ---
**Author:** ![FoDaddy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/fodaddy/32/717_2.png) [@FoDaddy](https://community.cartalk.com/u/FoDaddy)\ **Post date:** [April 14, 2009, 3:53pm UTC](https://community.cartalk.com/t/tire-sizes/28990/7 "2009-04-14T15:53:26Z")
It is folly to put mismatched tire sizes on a 4WD vehicle. While you may do fine in 2WD, as soon as you engage 4WD the likelihood of breaking universal joints or even busting you transfer case is high since 4WD vehicles don’t have center differentials to compensate for the difference in tire diameter. The difference in overall diameter in 235/70 and 235/75 tires is almost an inch. This is a significant difference. I would also advise against used tires. Always buy the best tires you can afford, Tires are highly important safety items; it’s not wise to skimp on safety. ---
**Author:** ![andrew\_j](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@andrew\_j](https://community.cartalk.com/u/andrew_j)\ **Post date:** [April 14, 2009, 4:18pm UTC](https://community.cartalk.com/t/tire-sizes/28990/8 "2009-04-14T16:18:06Z")
2003 Pathfinder(my brother’s) loaded model has three modes. Automatic(AWD), 4wd or 2wd. I believe the system is lifted from its close sibiling the Infiniti QX4 where it is ridiculous to have a primitive 1950’s Jeep era 4wd system in “luxury” SUV. Decent modern SUV’s have true 4wd and additionally AWD systems like the Jeep models and Land Rovers, Land Cruisers etc. ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [April 14, 2009, 4:57pm UTC](https://community.cartalk.com/t/tire-sizes/28990/9 "2009-04-14T16:57:15Z")
Does he live in Canada? After a quick google search…I was only able to find a AWD pathfinder in Canada and Europe. There is an All-Mode 4wd system that automatically switches to 4wd in adverse weather…HOWEVER this is still 4wd…which is very different from AWD. ---
**Author:** ![andrew\_j](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@andrew\_j](https://community.cartalk.com/u/andrew_j)\ **Post date:** [April 15, 2009, 1:49am UTC](https://community.cartalk.com/t/tire-sizes/28990/10 "2009-04-15T01:49:38Z")
He has a 2003 Pathfinder LE purchased in MA. It has stability control and All-Mode. According to this \>\>\>\> [http://www.hispanianews.com/archive/2003/02/14/05.htm](http://www.hispanianews.com/archive/2003/02/14/05.htm) and other sources including my brother who leaves it in Auto, it is AWD as I have witnessed it work, the rears spin a bit and front then spin when our ski house driveway gets drifted in. ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [April 15, 2009, 12:14pm UTC](https://community.cartalk.com/t/tire-sizes/28990/11 "2009-04-15T12:14:40Z")
I’ll agree this is something totally new…HOWEVER if you read it you’ll understand that it is NOT a AWD system…and thus NOT subject to the same problems of different tire sizes the AWD system is. AWD systems are far more sensitive to differences in tire sizes. ---
**Author:** ![andrew\_j](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@andrew\_j](https://community.cartalk.com/u/andrew_j)\ **Post date:** [April 15, 2009, 5:40pm UTC](https://community.cartalk.com/t/tire-sizes/28990/12 "2009-04-15T17:40:04Z")
The All-Mode system utilizes a wet multi-plate clutch design managed by a computerized electronic control unit, which allows up to 50 percent of available torque (infinitely adjustable) to reach the front wheels on demand. Sorry that is an AWD system. It sounds quite similar to the setup used in a Subaru WRX STI. I have no idea if the system is sensitive. The owners manual will state so possibly. ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [April 15, 2009, 6:18pm UTC](https://community.cartalk.com/t/tire-sizes/28990/13 "2009-04-15T18:18:50Z")
> computerized electronic control unit Sorry, but I still disagree…it is NOT the same as a AWD system. [http://autos.silive.com/Autos?tp=TR\_silive&category=research&temp\_type=detail&tl=3&model\_id=18864&car\_id=308168&tab=review](http://autos.silive.com/Autos?tp=TR_silive&category=research&temp_type=detail&tl=3&model_id=18864&car_id=308168&tab=review) It’s considered a 4WD system with a electronically controlled transfercase. Does the Subaru have a transfercase or a Viscous-coupling?? A viscous coupling will NOT tolerate different wheel dimensions. A 4wd system can. 4wd also has low range…AWD does NOT. ---
**Author:** ![andrew\_j](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@andrew\_j](https://community.cartalk.com/u/andrew_j)\ **Post date:** [April 16, 2009, 12:53am UTC](https://community.cartalk.com/t/tire-sizes/28990/14 "2009-04-16T00:53:46Z")
Not sure why you do not believe it is AWD. It is and a good system with a manual override for 4wd (center diff or transfer case locker). [http://www.infinitihelp.com/models/2001/qx4/](http://www.infinitihelp.com/models/2001/qx4/) = Nissan Pathfinder LE AWD in 2003 The All-Mode 4WD system provides a superior driving experience on and off the pavement, utilizing all-wheel drive technology derived from Nissan’s world-class Skyline GT-R sports coupe (rather than traditional truck-based systems). All-Mode 4WD was designed to instantly distribute torque to the front wheels (up to 50 percent can go to the front wheels on demand) resulting in optimal traction with improved fuel economy and enhanced cornering capability. Great system IMHO especially when you understand its roots. ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [April 16, 2009, 1:06am UTC](https://community.cartalk.com/t/tire-sizes/28990/15 "2009-04-16T01:06:22Z")
Used tires? It has always seemed to me that buying used tires is sort of like going to a house of ill repute in search of a faithful woman to marry. You might find a “nice girl” at that place, but there is a very strong chance that the girls there have a past (as well as a present) that is none too desirable–even if their outward appearance is good. In a similar sense, I don’t want to have to trust my life to tires that may have a questionable past, despite having a good appearance. ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [April 16, 2009, 1:35am UTC](https://community.cartalk.com/t/tire-sizes/28990/16 "2009-04-16T01:35:29Z")
I’m NOT saying it’s NOT a great system. But I just don’t see it as the same as AWD. AWD has some inherent problems which this system doesn’t have. ---
**Author:** ![andrew\_j](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@andrew\_j](https://community.cartalk.com/u/andrew_j)\ **Post date:** [April 16, 2009, 2:16am UTC](https://community.cartalk.com/t/tire-sizes/28990/17 "2009-04-16T02:16:04Z")
Semantics. AWD means to me the opposing axle can have power driven to it and run at varying speeds or torque. 4wd means to me the front and rear axle run at the exact same rotational speed (eg no slip). IMHO best systems combine both at the driver’s discretion. ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [April 16, 2009, 2:45am UTC](https://community.cartalk.com/t/tire-sizes/28990/18 "2009-04-16T02:45:08Z")
You can safely go to four identical tires, a couple of sizes different than the original tires. Identical means that, if they are used, they must all four have nearly identical amounts of wear (within a small fraction of an inch). A small nail in the side wall? So what? Is the tire leaking? Even if it is leaking, you can put some stop leak in the tire. If that slows the leak to zero, or near zero, it’s fixed. If the nail head offends you, cut it off. Think about it. The nail is in rubber. Rubber is flexible. A small nail does NOT structurally affect the tire. Think of it as a beauty mark. I have safely driven with nails in my tires for years. ---
**Author:** ![andrew\_j](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@andrew\_j](https://community.cartalk.com/u/andrew_j)\ **Post date:** [April 16, 2009, 12:37pm UTC](https://community.cartalk.com/t/tire-sizes/28990/19 "2009-04-16T12:37:54Z")
Anything in a sidewall compromises strength. Some area’s I concur it makes no difference, others it may be like cutting the main support beam in a structure. It would take an engineering analysis to figure it out in each individual case. Are you an engineer? Life is short and tires are relatively cheap and have a significant role in vehicle safety. They sell cheap tires are plenty safe if taken care of properly and not patched together. ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [April 16, 2009, 12:55pm UTC](https://community.cartalk.com/t/tire-sizes/28990/20 "2009-04-16T12:55:26Z")
Andrew i, YOU prove your statements that, “Anything in a sidewall compromises strength…etc.” Are YOU a tire engineer? There are things where experience and judgement are more appropriate than impossible impositions of irrefutable proof. [Next page](https://community.cartalk.com/t/tire-sizes/28990.md?page=2)