Tires: too wide = no go?

[87 Turbo II]

Hey I have 13 by 6 wheels on the Rx-7 and I'm running 205s, when these get low on tread I plan on going up to 215s. I've got the clearance to not worry about rubbing but my friend posted on 240atlanta asking how wide he should go on 15 by 6 and they said anything over 205s would handle like ass. Now I always thought wider is better, but is it true that too wide for the wheel will make the handling WORSE? Does it have to do with the fact that it has to pincushion inward to fit the beads onto the rim or what? Let me know if 215s are still my best bet or if I should stick to 205s.

[Gilgamesh]

well it all depends on the tire.

good year or hoosier makes a tire for classes that have a limited wheel width. that the side wall is more then an inch outside the rim.

the solstice can fit 295s hoosiers on there.

but i would recomend getting those konigs with the 4x110 pattern. in 15x7.

then you have a good choice of tires.

[87 Turbo II]

well it all depends on the tire.

good year or hoosier makes a tire for classes that have a limited wheel width. that the side wall is more then an inch outside the rim.

the solstice can fit 295s hoosiers on there.

but i would recomend getting those konigs with the 4x110 pattern. in 15x7.

then you have a good choice of tires.

I already got aftermarket wheels, they're 13X6. Also the Konigs are too expensive, I wanna go from 205/60R/13s to 215/60R/13s I originally has 185/70R/13s and the car came stock with 165/70R/13 on 13X5.5s

[trista]

i wouldnt go wider than 205's...

i have 155/70R13 on my 13x7 riken. :]

[87 Turbo II]

I want to know WHY not to go past 205, what is it that makes an oversized tire suck at handling? I still believe that wider is always better, if it mounts on the wheel, I htought it was fair game. If the truth is otherwise, I want an EXPLINATION.

[trista]

I want to know WHY not to go past 205, what is it that makes an oversized tire suck at handling? I still believe that wider is always better, if it mounts on the wheel, I htought it was fair game. If the truth is otherwise, I want an EXPLINATION.

if you are trying to autocross the car or go on the mts runs with it. taking turns with an over sized tires on a wheels is kind of dangerous, the tires could pop off the wheels.

[87 Turbo II]

if you are trying to autocross the car or go on the mts runs with it. taking turns with an over sized tires on a wheels is kind of dangerous, the tires could pop off the wheels.

Ok, that works, 205s it is then. Thanks man, that's what I wanted.

[Bruce Leroy]

I doubt that 225's would come off the bead when you are driving... But i could be wrong... I would go with the 205's anyways.... Maybe 215's.

Apparently there have been many question regarding tire width to wheel width correlation so, here is a sort of technical response.

While tires can and do fit a wheel width range (i.e. a 225/45-17 range is 7" - 9") there are serious issues going outside that range

here's poorly executed picture to base the conversation on



in figure "A"
the tire size is properly mated to the wheel width. That type of setup would allow the tire to achieve the best possible control of the contact patch and offer the most support for the weight of the vehicle.

in figure "B"
the tire is too narrow for the wheel so, as you can clearly see the sidewalls are not anywhere close to verticle which would cause the tire to not have the proper load capacity or control of the contact patch thus reducing it's ability to perform it's job and creating more heat.

in figure "C"
the tire is way too wide for the wheel and just as in figure "B" the load capacity is adversely effected as well as contact patch control because of the excessive sidewall roll over.

in both figure "B" and "C" the sidewall of the tires are under extreme stress which can cause several things to happen.


just to mention a few:
#1.) catastrophic sidewall failure due to load issues
#2.) complete tire failure due to excessive heat being generated by additional flex and/or roll of the sidewall
#3.) adversely effected handling since the sidewalls can not control the contact area properly
#4.) beaking of the tire bead area under extreme cornering causing immediate loss of air pressure and vehicular control.

I mentioned load capacity as a very important issue in my previous statements so, let's consider the idea of running a capacity that is too low .... what happens:
the tire is put into a condition where it can support the car at a static rest point but, when driven aggressively the sidewalls are so over worked they can not properly control the contact patch of the tire allowing for excessive sidewall roll-over, irregular wear tread block and contact patch flex which robs the tires performance ability and grip. also the added flexing of the tire will increase the heat it generates which can make a tire feel really slippery .... and if you can't utilize the power you're making nothing else matters afterall the tires are the only item on your car touching the road ....

A good way to understand this is: let's say I just put a 100lb. back pack on you .... you can stand there for quite a while (that's your car sitting in a parking lot) now go run up and down some stairs with that back pack .... that's normal driving and you can't do that very well, nearly as fast or for very long before your legs give out .... after you've recovered enough to walk (let the car rest once you arrive at the venue for your autoX), take a 500 meter sprint through deep sand, that's your autoX and you will most likely not make it to the finish without falling atleast once if you can finish at all.

[Bruce Leroy]

I don't know why i thought u wanted 225's....

reading > me

[87 Turbo II]

Wow that's EXACTLY what I wanted. REPS to both of you. I'll kep it 205 then.

[trista]

Ok, that works, 205s it is then. Thanks man, that's what I wanted.

uhhh im a chick. your welcome anyways! +++

[87 Turbo II]

uhhh im a chick. your welcome anyways! +++

Thanks chick!

better?

[trista]

Thanks chick!

better?

[Shadow102]

215 would be the max on a 6" rim. What's going to happen is your going to get a lot of foward and braking grip but what's going to end up happening in a hard corner is the tire will roll over, you can combat this with some extra tire presure but where its going to really bite you is in hard left right transitions.

205 may even be too big you probably may want to look at a 195 since the rx7 isn't a huge torque monster and the brakes aren't huge

[87 Turbo II]

215 would be the max on a 6" rim. What's going to happen is your going to get a lot of foward and braking grip but what's going to end up happening in a hard corner is the tire will roll over, you can combat this with some extra tire presure but where its going to really bite you is in hard left right transitions.

205 may even be too big you probably may want to look at a 195 since the rx7 isn't a huge torque monster and the brakes aren't huge

well these 205s make the car handle infinitely better than the 185s did so I don't think I'm getting roll issues at this width. I'm going to keep it here. Thanks for your input.I'm looking forward to getting back out into the autocrossing scene. you gonig to be at the T-field autoX on March 29th?

[Shadow102]

well these 205s make the car handle infinitely better than the 185s did so I don't think I'm getting roll issues at this width. I'm going to keep it here. Thanks for your input.I'm looking forward to getting back out into the autocrossing scene. you gonig to be at the T-field autoX on March 29th?

Nah I probably won't make it until april. I still gotta get tires, a cat back, and some shocks to go with the tein springs going on this week.