Regular Training Runs-Pace?

[Nate]

I'm trying to run a sub 3:15 (I figure 7:13/mi. pace) at Grandma's Marathon in June.  My weekly mileage is between 45-50 miles. 
I normally run at least one combination of a goal pace/tempo run (i.e. 4 @ GP of 7:13/mi. and 3 @ T of 6:50/mi.= 7 total miles)per week.  I run 5 days a week and physically I feel that I could run some of those other miles closer to tempo or at least goal pace.  Many of the miles I run are around 7:30 pace other than those of the combo run and the weekend long run is a bit slower too.  I guess I am just not wanting to burn out with more than 2 months of training left. I ran a 17 miler on Sunday at 7:50 pace without feeling too fatigued, a bit in the legs is all.  I was not trying to run goal pace in any of the miles but felt like I ran faster than a time of 2:13/7:50 GP and concerned that this is too slow.  This will be my 6th marathon and my PR is 3:36.  I have never had a goal this fast before.  I'm way ahead of previous training times at similar distances, but still concerned I need to push it a bit more.
Any recommendations out there?

[Sasha Pachev]

How fast can you run a 5 K? If faster than 20 minutes, then your actual marathon race pace, or even dream goal pace are going to be slower than your true marathon pace. In that case it is safe to go  faster in your regular runs than what pacing charts and formulas predict. Those calculations are taken from  a guy running 90+ miles a week who has already realized most of his speed potential in the marathon and are merely extrapolated into a slower range.  However, if running faster means you go less, you should slow down. When lacking aerobic power (a condition present among 99% of marathon finishers) every two additional miles at any pace are worth much more than one fast mile.

[Matthew Rowley]

Nate we are in the same position I am trying to figure out if I should attempt to run a 3:10 in Ogden so I thing you will be releaved to know
3:10 is (7:15/mi pace), 3:15 is (7:26/mi pace).  Good luck on figuring things out.  I have been gradually adding miles and should peak out at 60 miles a week.  My PR of the Marathon is 3:34, so I will be looking to see how you do.  I don't have any advice on what you should do, but it is nice to see someone struggling with the same questions or issues.

[Nate]

Sasha, thanks for the reply.  I did run a 19:48 5K in poor conditions.  I will note the 2 of any mile to that of 1 fast mile.  Thanks again.

[Nate]

Matthew, we will see how it goes.  I'm considering it a "7:15" pace for longer water breaks, family photo op., etc. plus trying to mentally trick myself into running at that pace, which should put me in under my time, but there are many variables out there as you know.  Thanks for the reply.

[Sasha Pachev]

I will note the 2 of any mile to that of 1 fast mile.  Thanks again.

Just to clarify in case there is confusion - this is not a hard number rule, maybe not even a rule of thumb. What I was trying to say is when aerobic development lacks going further is preferable to going faster.