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Discussion Starter #1
So I just installed wheels and tires yesterday. I went from the stock 195/60R15 tires on the stock 15x6 +52.5 wheels to 215/35ZR18 Nitto Neogens on 18x8 +35 Team Dynamics Pro Race 1.2 wheels.

I bought the tires from Discount Tire Direct and one of the sales representatives called me about an unrelated order issue. He also mentioned that they recommend the new tires to be inflated to 46 PSI. The maximum pressure on the new tires is 50 PSI. Keep in mind that the recommended tire pressure for the stock tires is 30-32 PSI (I don't remember which right now).

I had my friend (who is a senior Nissan technician) mount and balance the tires on the wheels. He inflated the tires to 35 PSI because that is what he runs in the low profile tires on one of his Nissans. I told him about the 46 PSI recommendation and he said that was awfully high, considering the maximum pressure rating. To me, the tires look like a little more air pressure wouldn't hurt.

Does anyone here run 35 series tires or have a recommendation for what tire pressure I should run?
 

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Does anyone here run 35 series tires or have a recommendation for what tire pressure I should run?
The 2012+ low profile tires have an aspect ratio of 40 and they're rated at 39psi. Many people still inflate them to 42. So 46 doesn't sound out of the question, but it'd probably make a harsh ride... not that you care - seeing as how you went with such a low profile tire in the first place.

God, I envy how smooth your roads must be.
 

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Discussion Starter #3
The 2012+ low profile tires have an aspect ratio of 40 and they're rated at 39psi. Many people still inflate them to 42. So 46 doesn't sound out of the question, but it'd probably make a harsh ride... not that you care - seeing as how you went with such a low profile tire in the first place.

God, I envy how smooth your roads must be.
Yeah, not too worried about the ride being too harsh. Actually, our roads suck. But I don't drive too much. I also have a fully built suspension, so the ride is pretty stiff as it is, not to mention all three poly motor mounts adding some vibration. I just want optimum tire pressure. I'll try the 46 PSI for a little while.
 

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Just to add, you can't go by how they look as far as pressure. I'd start at 35-36lbs. Did you get a alignment done or checked= for toe front & rear?
 

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Discussion Starter #5
Just to add, you can't go by how they look as far as pressure. I'd start at 35-36lbs. Did you get a alignment done or checked= for toe front & rear?
Yeah, I know. They just don't look quite right, though. They are already inflated to 35 PSI. I recently got an alignment in June or July when I installed all of the suspension parts.
 

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w/ my magic bag
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Yeah, I know. They just don't look quite right, though. They are already inflated to 35 PSI. I recently got an alignment in June or July when I installed all of the suspension parts.
Your probablity not use of looking at low profile tires. Check & look at other ppl tire/wheel combo's. Checkout your next door neighbors to see what they're running on they're Donk's in your hood.[grinking]
 

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Discussion Starter #7
Your probablity not use of looking at low profile tires. Check & look at other ppl tire/wheel combo's. Checkout your next door neighbors to see what they're running on they're Donk's in your hood.[grinking]
It's like you know who lives in my apartment complex.[80?]
 

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What's the load rating of the 195 tire? (and at what pressure)

What's the load rating of the 215 tire? (and at what pressure)



Say the 195 tire rating is 1000lbs at 40 psi.

Load rating of tire is roughly linear with pressure.

So at 30psi, the 195 tire load rating is 750 lbs.


If the 215 tire load rating is 1000lbs at 50 psi, you need to inflate it to 37.5psi to get the same 750lb load rating......


Adjust pressure of 215 tire to get same load rating (if 215 tire was 1500 lbs, you'd only need 25 psi)
 

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A lower aspect ratio tire will require a higher pressure as the rim of the wheel well be closer to the road surface. Higher tire pressures allow the tire to remain firmer for road imperfections and well allow the tire to run cooler. If 46 psi is what was recommended then that would be my starting point.

Maximum cold inflation numbers are tested by manufacturers to be safe, so don't be afraid of running at or near them. If you're setting pressures correctly then you will always be safer with a higher pressure than a lower pressure.
 

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It's like you know who lives in my apartment complex.[80?]
Jack up the foci & install a set of 30's & then you can become the [grinking]Focus Donk in your complex.[bootyshake][lockdance][cheers][thumb][cool][wave][clap][strongman][thumb]
 

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Fords recommended for a MK1 RS is 33psi in front and 30psi in the rear with a 225/40R18. Thats as close to a manufacturer spec you'll get for your set up. Just throwin that out there.
 

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Discussion Starter #13
The OE tires are Hankook Optimo H725. They are rated at 1190 lbs at 44 psi. The new tires are Nitto Neo Gen, rated at 1102 lbs at 50 psi.

Recommended tire pressure for stock wheels and tires is 32 psi. So if my calculations are correct, I should be running about 39 psi in the new tires.
 
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